Induction of Efficacy Expectancies in an Ambulatory Smartphone-Based Digital Placebo Mental Health Intervention: Randomized Controlled Trial

Background There is certain evidence on the efficacy of smartphone-based mental health interventions. However, the mechanisms of action remain unclear. Placebo effects contribute to the efficacy of face-to-face mental health interventions and may also be a potential mechanism of action in smartphone-based interventions. Objective This study aimed to investigate whether different types of efficacy expectancies as potential factors underlying placebo effects could be successfully induced in a smartphone-based digital placebo mental health intervention, ostensibly targeting mood and stress. Methods We conducted a randomized, controlled, single-blinded, superiority trial with a multi-arm parallel design. Participants underwent an Android smartphone-based digital placebo mental health intervention for 20 days. We induced prospective efficacy expectancies via initial instructions on the purpose of the intervention and retrospective efficacy expectancies via feedback on the success of the intervention at days 1, 4, 7, 10, and 13. A total of 132 healthy participants were randomized to a prospective expectancy–only condition (n=33), a retrospective expectancy–only condition (n=33), a combined expectancy condition (n=34), or a control condition (n=32). As the endpoint, we assessed changes in efficacy expectancies with the Credibility Expectancy Questionnaire, before the intervention and on days 1, 7, 14, and 20. For statistical analyses, we used a random effects model for the intention-to-treat sample, with intervention day as time variable and condition as two factors: prospective expectancy (yes vs no) and retrospective expectancy (yes vs no), allowed to vary over participant and intervention day. Results Credibility (β=−1.63; 95% CI −2.37 to −0.89; P<.001) and expectancy (β=−0.77; 95% CI −1.49 to −0.05; P=.04) decreased across the intervention days. For credibility and expectancy, we found significant three-way interactions: intervention day×prospective expectancy×retrospective expectancy (credibility: β=2.05; 95% CI 0.60-3.50; P=.006; expectancy: β=1.55; 95% CI 0.14-2.95; P=.03), suggesting that efficacy expectancies decreased least in the combined expectancy condition and the control condition. Conclusions To our knowledge, this is the first empirical study investigating whether efficacy expectancies can be successfully induced in a specifically designed placebo smartphone-based mental health intervention. Our findings may pave the way to diminish or exploit digital placebo effects and help to improve the efficacy of digital mental health interventions. Trial Registration Clinicaltrials.gov NCT02365220; https://clinicaltrials.gov/ct2/show/NCT02365220.

Manuscript tracking number * If this is a JMIR submission, please provide the manuscript tracking number under "other" (The ms tracking number can be found in the submission acknowledgement email, or when you login as author in JMIR. If the paper is already published in JMIR, then the ms tracking number is the four-digit number at the end of the DOI, to be found at the bottom of each published article in JMIR) ms #20329 1a) Does your paper address CONSORT item 1a? * Identify the mode of delivery. Preferably use "web-based" and/or "mobile" and/or "electronic game" in the title. Avoid ambiguous terms like "online", "virtual", "interactive". Use "Internet-based" only if Intervention includes non-web-based Internet components (e.g. email), use "computer-based" or "electronic" only if osine products are used. Use "virtual" only in the context of "virtual reality" (3-D worlds). Use "online" only in the context of "online support groups". Complement or substitute product names with broader terms for the class of products (such as "mobile" or "smart phone" instead of "iphone"), especially if the application runs on different platforms.

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Does your paper address subitem 1a-i? * Copy and paste relevant sections from manuscript title (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "Induction of Ekcacy Expectancies in an Ambulatory Smartphone-based Digital Placebo Mental Health Intervention: Randomized Controlled Trial"

1a-ii) Non-web-based components or impo"ant co-interventions in title
Mention non-web-based components or important co-interventions in title, if any (e.g., "with telephone support"). https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…l=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full subitem not at all important 1 2 3 4 5 essential 1b) ABSTRACT: Structured summary of trial design, methods, results, and conclusions NPT extension: Description of experimental treatment, comparator, care providers, centers, and blinding status.
Does your paper address subitem 1a-ii?
Copy and paste relevant sections from manuscript title (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study Not applicable.

1a-iii) Primary condition or target group in the title
Mention primary condition or target group in the title, if any (e.g., "for children with Type I Diabetes") Example: A Web-based and Mobile Intervention with Telephone Support for Children with Type I Diabetes: Randomized Controlled Trial

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Does your paper address subitem 1a-iii? * Copy and paste relevant sections from manuscript title (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study Less relevant in our study, because inclusion of healthy participants. To avoid that the title may become too long, we focused on terms regarding the study design in the title. https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full subitem not at all important 1 2 3 4 5 essential 1b-i) Key features/functionalities/components of the intervention and comparator in the METHODS section of the ABSTRACT Mention key features/functionalities/components of the intervention and comparator in the abstract. If possible, also mention theories and principles used for designing the site. Keep in mind the needs of systematic reviewers and indexers by including important synonyms. (Note: Only report in the abstract what the main paper is reporting. If this information is missing from the main body of text, consider adding it)

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Does your paper address subitem 1b-i? * Copy and paste relevant sections from the manuscript abstract (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "We conducted a randomized, controlled, single-blinded superiority trial with a multi-arm parallel design. Participants underwent an Android-based smartphonebased digital placebo mental health intervention for 20 days. We induced prospective ekcacy expectancies via initial instructions on the purpose of the intervention and retrospective ekcacy expectancies via feedback on the success of the intervention at days 1, 4, 7, 10, and 13. 132 healthy participants were randomized to a prospective expectancy only (n=33), a retrospective expectancy only (n=33), a combined expectancy (n=34), or a control condition (n=32)." https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full subitem not at all important 1 2 3 4 5 essential subitem not at all important 1 2 3 4 5 essential 1b-ii) Level of human involvement in the METHODS section of the ABSTRACT Clarify the level of human involvement in the abstract, e.g., use phrases like "fully automated" vs. "therapist/nurse/care provider/physician-assisted" (mention number and expertise of providers involved, if any). (Note: Only report in the abstract what the main paper is reporting. If this information is missing from the main body of text, consider adding it)

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Does your paper address subitem 1b-ii?
Copy and paste relevant sections from the manuscript abstract (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study Meine Antwort 1b-iii) Open vs. closed, web-based (self-assessment) vs. face-to-face assessments in the METHODS section of the ABSTRACT Mention how participants were recruited (online vs. osine), e.g., from an open access website or from a clinic or a closed online user group (closed usergroup trial), and clarify if this was a purely web-based trial, or there were face-to-face components (as part of the intervention or for assessment). Clearly say if outcomes were self-assessed through questionnaires (as common in web-based trials Does your paper address subitem 1b-iii? Copy and paste relevant sections from the manuscript abstract (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study Meine Antwort 1b-iv) RESULTS section in abstract must contain use data Report number of participants enrolled/assessed in each group, the use/uptake of the intervention (e.g., attrition/adherence metrics, use over time, number of logins etc.), in addition to primary/secondary outcomes. (Note: Only report in the abstract what the main paper is reporting. If this information is missing from the main body of text, consider adding it)
Copy and paste relevant sections from the manuscript abstract (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study

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Does your paper address subitem 2a-i? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "In sum, there is the urgent need to i) further scrutinize smartphone-based mental health interventions in the context of the WHO grand challenge on the development of mobile and IT technologies to increase access to evidence-based care, ii) explore potential mechanisms of change underlying smartphone-based mental health interventions that are already widespread however little validated, and iii) scrutinize and exploit ekcacy expectancies as a potential factor underlying placebo effects, by means of smartphone-based interventions with respect to their methodological advantages.

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Does your paper address subitem 2a-ii? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "Previous studies in the context of digital placebo effects introduced the concept [13], focused on methodological recommendations for RCTs of smartphone-based interventions [21,22] or utilized a sham version of an active app as control condition [23]. However, to the best of our knowledge, no study investigated ekcacy expectancies as a potential mechanism of the digital placebo effect in a particularly designed inert smartphone-based mental health intervention." https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full METHODS 3a) Description of trial design (such as parallel, factorial) including allocation ratio 3b) Impo"ant changes to methods a#er trial commencement (such as eligibility criteria), with reasons Does your paper address CONSORT subitem 2b? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "We hypothesized that trajectories of ekcacy expectancies throughout the smartphone-based placebo mental health intervention differed between conditions. Furthermore, we hypothesized that ekcacy expectancies were highest in the combined expectancy condition, followed on a comparable level in the prospective expectancy condition and the retrospective expectancy condition, and lowest in the control condition." Does your paper address CONSORT subitem 3a? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "We report the results of a randomized, controlled, single-blinded superiority trial with a multi-arm parallel design, registered at ClinicalTrials.gov (IdentiPer: NCT02365220)." https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full subitem not at all important 1 2 3 4 5 essential 4a) Eligibility criteria for pa"icipants Does your paper address CONSORT subitem 3b? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study Not relevant for our study.

3b-i) Bug %xes, Downtimes, Content Changes
Bug Pxes, Downtimes, Content Changes: ehealth systems are often dynamic systems. A description of changes to methods therefore also includes important changes made on the intervention or comparator during the trial (e.g., major bug Pxes or changes in the functionality or content) (5-iii) and other "unexpected events" that may have intuenced study design such as staff changes, system failures/downtimes, etc. [2].

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Does your paper address subitem 3b-i?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "In cases of unexpected events, the Master's students communicated via e-mail with participants, which was reduced to a necessary extent." https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full subitem not at all important 1 2 3 4 5 essential Does your paper address CONSORT subitem 4a? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "The following inclusion criteria applied: no severe visual impairment, no dyschromatopsia, no severe defective hearing, no regular intake of medication (e.g., antidepressants), and no severe mental disorders (e.g., schizophrenia, other psychotic disorders, or severe affective disorders)."

4a-i) Computer / Internet literacy
Computer / Internet literacy is often an implicit "de facto" eligibility criterion -this should be explicitly clariPed.

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Does your paper address subitem 4a-i?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "We introduced them to the applications they would use during the 20 intervention days." "We instructed participants to download and install the ohmage app [29] from the Google Play Store on their smartphones." https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full subitem not at all important 1 2 3 4 5 essential 4a-ii) Open vs. closed, web-based vs. face-to-face assessments: Open vs. closed, web-based vs. face-to-face assessments: Mention how participants were recruited (online vs. osine), e.g., from an open access website or from a clinic, and clarify if this was a purely webbased trial, or there were face-to-face components (as part of the intervention or for assessment), i.e., to what degree got the study team to know the participant. In online-only trials, clarify if participants were quasi-anonymous and whether having multiple identities was possible or whether technical or logistical measures (e.g., cookies, email conPrmation, phone calls) were used to detect/prevent these.

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Does your paper address subitem 4a-ii? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "The study consisted of an introductory session and 20 consecutive days of ambulatory smartphone-based intervention (see Multimedia Appendix 2)." "We recruited participants from the Bachelor student body of the University of Basel, Switzerland, in Psychology and other lectures, where we presented our study. Advertisements of our study were posted on the website of the psychology students' Facebook group and on local bulletin boards of the Department of Psychology." https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full subitem not at all important 1 2 3 4 5 essential 4b) Se$ings and locations where the data were collected 4a-iii) Information giving during recruitment Information given during recruitment. Specify how participants were briefed for recruitment and in the informed consent procedures (e.g., publish the informed consent documentation as appendix, see also item X26), as this information may have an effect on user self-selection, user expectation and may also bias results.
Does your paper address subitem 4a-iii?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study

Meine Antwort
Does your paper address CONSORT subitem 4b? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "We recruited participants from the Bachelor student body of the University of Basel, Switzerland, in Psychology and other lectures, where we presented our study." "The study consisted of an introductory session and 20 consecutive days of ambulatory smartphone-based intervention (see Multimedia Appendix 2)." https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full subitem not at all important 1 2 3 4 5 essential 4b-i) Repo" if outcomes were (self-)assessed through online questionnaires Clearly report if outcomes were (self-)assessed through online questionnaires (as common in web-based trials) or otherwise.

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Does your paper address subitem 4b-i? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "The detailed procedure of each session is being illustrated in Multimedia Appendix 2. The placebo mental health intervention consisted of a green picture or a mock sound, delivered in a video Ple on EFS Survey which participants accessed via their Android-based smartphones. The videos lasted for two minutes each and alternated daily between green color and mock sound. Regarding the mock sound, we told participants in the initial instructions that the sound would be a very soft tone acoustically not perceivable for the human ear and completely innocuous. On intervention days 1, 4, 7, 10, and 13, we asked participants to take a self-portrait with their smartphone camera within the ohmage app. After this second selfportrait, we provided participants with written feedback regarding the self-portrait in the ohmage app which we had programmed in advance. Does your paper address subitem 4b-ii?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study Meine Antwort

5-i) Mention names, credential, a!liations of the developers, sponsors, and owners
Mention names, credential, akliations of the developers, sponsors, and owners [6] (if authors/evaluators are owners or developer of the software, this needs to be declared in a "Contict of interest" section or mentioned elsewhere in the manuscript). https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full subitem not at all important 1 2 3 4 5 essential Does your paper address subitem 5-i?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study Meine Antwort

5-ii) Describe the history/development process
Describe the history/development process of the application and previous formative evaluations (e.g., focus groups, usability testing), as these will have an impact on adoption/use rates and help with interpreting results.

Does your paper address subitem 5-ii?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full subitem not at all important

5-iii) Revisions and updating
Revisions and updating. Clearly mention the date and/or version number of the application/intervention (and comparator, if applicable) evaluated, or describe whether the intervention underwent major changes during the evaluation process, or whether the development and/or content was "frozen" during the trial. Describe dynamic components such as news feeds or changing content which may have an impact on the replicability of the intervention (for unexpected events see item 3b).

Does your paper address subitem 5-iii?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study Meine Antwort

5-iv) Quality assurance methods
Provide information on quality assurance methods to ensure accuracy and quality of information provided [1], if applicable.
Does your paper address subitem 5-iv?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full subitem not at all important 1 2 3 4 5 essential subitem not at all important 1 2 3 4 5 essential 5-v) Ensure replicability by publishing the source code, and/or providing screenshots/screen-capture video, and/or providing &owcha"s of the algorithms used Ensure replicability by publishing the source code, and/or providing screenshots/screen-capture video, and/or providing towcharts of the algorithms used. Replicability (i.e., other researchers should in principle be able to replicate the study) is a hallmark of scientiPc reporting.

Does your paper address subitem 5-v?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study Meine Antwort

5-vi) Digital preservation
Digital preservation: Provide the URL of the application, but as the intervention is likely to change or disappear over the course of the years; also make sure the intervention is archived (Internet Archive, webcitation.org, and/or publishing the source code or screenshots/videos alongside the article). As pages behind login screens cannot be archived, consider creating demo pages which are accessible without login. https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full subitem not at all important 1 2 3 4 5 essential Does your paper address subitem 5-vi?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study Meine Antwort

5-vii) Access
Access: Describe how participants accessed the application, in what setting/context, if they had to pay (or were paid) or not, whether they had to be a member of speciPc group. If known, describe how participants obtained "access to the platform and Internet" [1]. To ensure access for editors/reviewers/readers, consider to provide a "backdoor" login account or demo mode for reviewers/readers to explore the application (also important for archiving purposes, see vi).

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Does your paper address subitem 5-vii? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "We compensated Psychology students with 12 signatures for study completion, which they required as parts of their Bachelor's studies. If participants dropped out before completion, compensation was granted proportionally. For students of other faculties, we offered participation in a lottery drawing for a tablet computer as

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Does your paper address subitem 5-viii? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study " Ohmage is an open mobile system consisting of a smartphone application for self-reported data collection and a server system for web-based data storage, management, and administration. We set up and maintained our own ohmage server at the IT division of the Department of Psychology."

5-ix) Describe use parameters
Describe use parameters (e.g., intended "doses" and optimal timing for use Does your paper address subitem 5-ix? Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study Meine Antwort

5-x) Clarify the level of human involvement
Clarify the level of human involvement (care providers or health professionals, also technical assistance) in the e-intervention or as co-intervention (detail number and expertise of professionals involved, if any, as well as "type of assistance offered, the timing and frequency of the support, how it is initiated, and the medium by which the assistance is delivered". It may be necessary to distinguish between the level of human involvement required for the trial, and the level of human involvement required for a routine application outside of a RCT setting (discuss under item 21 -generalizability).
Does your paper address subitem 5-x?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full subitem not at all important 1 2 3 4 5 essential subitem not at all important 1 2 3 4 5 essential 5-xi) Repo" any prompts/reminders used Report any prompts/reminders used: Clarify if there were prompts (letters, emails, phone calls, SMS) to use the application, what triggered them, frequency etc. It may be necessary to distinguish between the level of prompts/reminders required for the trial, and the level of prompts/reminders for a routine application outside of a RCT setting (discuss under item 21 -generalizability).

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Does your paper address subitem 5-xi? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "Participants were enrolled and assigned to the different conditions by two Master's students, according to predePned rules of a standard operating procedure, which included the utilization of predePned impersonal standard e-mails resp. SMS for inviting and reminding participants to study participation."

5-xii) Describe any co-interventions (incl. training/suppo")
Describe any co-interventions (incl. training/support): Clearly state any interventions that are provided in addition to the targeted eHealth intervention, as ehealth intervention may not be designed as stand-alone intervention. This includes training sessions and support [1]. It may be necessary to distinguish between the level of training required for the trial, and the level of training for a routine application outside of a RCT setting (discuss under item 21 -generalizability. Auswahl löschen https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full 6a) Completely de!ned pre-speci!ed primary and secondary outcome measures, including how and when they were assessed Does your paper address subitem 5-xii? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "In the introductory session, we informed participants about the aim and procedure of the study, and assessed inclusion criteria, sociodemographic information, and information on their general and mental health (Patient Health Questionnaire -German version [25,26], Perceived Stress Scale -10-items version [27,28]). Irrespective of potential condition assignment, we informed all participants that in our study we would be interested in how mood and perceived stress tuctuated in daily life, and whether smartphones would be suitable to assess their temporal trajectories. We instructed participants to download and install the ohmage app [29] from the Google Play Store on their Android-based smartphones. " Does your paper address CONSORT subitem 6a? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study subitem not at all important 1 2 3 4 5 essential 7b) When applicable, explanation of any interim analyses and stopping guidelines 8a) Method used to generate the random allocation sequence NPT: When applicable, how care providers were allocated to each trial group 7a-i) Describe whether and how expected a'rition was taken into account when calculating the sample size Describe whether and how expected attrition was taken into account when calculating the sample size.
Does your paper address subitem 7a-i?
Copy and paste relevant sections from manuscript title (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study

Meine Antwort
Does your paper address CONSORT subitem 7b? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study Not applicable. https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full 8b) Type of randomisation; details of any restriction (such as blocking and block size) Does your paper address CONSORT subitem 8a? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "Participants who met inclusion criteria were randomly assigned to one of the four conditions, as well as to whether they would start the ambulatory smartphonebased placebo exposure by either green color or mock sound, resulting in eight groups (1:1:1:1:1:1:1:1). Randomization was stratiPed by sex and included a randomly permuted block procedure with Pxed block sizes of 8, 16, and 24 participants. To account for the presumably higher percentage of female participants, the female strata included six blocks grouped into two pairs of three blocks, each of them containing one block for each of the three block sizes, 9) Mechanism used to implement the random allocation sequence (such as sequentially numbered containers), describing any steps taken to conceal the sequence until interventions were assigned Does your paper address CONSORT subitem 8b? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "Participants who met inclusion criteria were randomly assigned to one of the four conditions, as well as to whether they would start the ambulatory smartphonebased placebo exposure by either green color or mock sound, resulting in eight groups (1:1:1:1:1:1:1:1). Randomization was stratiPed by sex and included a randomly permuted block procedure with Pxed block sizes of 8, 16, and 24 participants. To account for the presumably higher percentage of female participants, the female strata included six blocks grouped into two pairs of three blocks, each of them containing one block for each of the three block sizes, whereas the male strata included only three blocks, one block for each block size. Randomization was done in RStudio (Version 0.99.891; R Project for Statistical Computing [32]) by an independent party." 10) Who generated the random allocation sequence, who enrolled pa"icipants, and who assigned pa"icipants to interventions Does your paper address CONSORT subitem 9? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "Participants who met inclusion criteria were randomly assigned to one of the four conditions, as well as to whether they would start the ambulatory smartphonebased placebo exposure by either green color or mock sound, resulting in eight groups (1:1:1:1:1:1:1:1). Randomization was stratiPed by sex and included a randomly permuted block procedure with Pxed block sizes of 8, 16, and 24 participants. To account for the presumably higher percentage of female participants, the female strata included six blocks grouped into two pairs of three blocks, each of them containing one block for each of the three block sizes, whereas the male strata included only three blocks, one block for each block size. Randomization was done in RStudio (Version 0.99.891; R Project for Statistical Computing [32]) by an independent party." 11a) If done, who was blinded a#er assignment to interventions (for example, pa"icipants, care providers, those assessing outcomes) and how NPT: Whether or not administering co-interventions were blinded to group assignment subitem not at all important 1 2 3 4 5 essential Does your paper address CONSORT subitem 10? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "Randomization was done in RStudio (Version 0.99.891; R Project for Statistical Computing [32]) by an independent party. Participants were enrolled and assigned to the different conditions by two Master's students, according to predePned rules of a standard operating procedure, which included the utilization of predePned impersonal standard e-mails resp. SMS for inviting and reminding participants to study participation. In cases of unexpected events, the Master's students communicated via e-mail with participants, which was reduced to a necessary extent. Eligible participants were blinded to their allocation. At the end of intervention day 20, we debriefed participants via ohmage app on the actual aims of the study and that we had exposed them to a placebo intervention." 11a-i) Specify who was blinded, and who wasn't Specify who was blinded, and who wasn't. Usually, in web-based trials it is not possible to blind the participants [1, 3] (this should be clearly acknowledged), but it may be possible to blind outcome assessors, those doing data analysis or those administering co-interventions (if any

11b) If relevant, description of the similarity of interventions
(this item is usually not relevant for ehealth trials as it refers to similarity of a placebo or sham intervention to a active medication/intervention) Does your paper address subitem 11a-i? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "Eligible participants were blinded to their allocation." 11a-ii) Discuss e.g., whether pa"icipants knew which intervention was the "intervention of interest" and which one was the "comparator" Informed consent procedures (4a-ii) can create biases and certain expectations -discuss e.g., whether participants knew which intervention was the "intervention of interest" and which one was the "comparator".

Does your paper address subitem 11a-ii?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full Does your paper address CONSORT subitem 11b? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "Ekcacy expectancies in the four conditions were induced via two ways: 1) the instructions on the purpose of the study on intervention day 1 and 2) the written feedback following the second (i.e., post-placebo-intervention) self-portrait on intervention days 1, 7, 14, and 20. While the initial instructions in our experiment served to induce prospective expectancies in participants, the feedback on the selfportraits served to induce retrospective expectancies (see Figure 1 for fourfold table of the four conditions): 1) Control: on intervention day 1, participants received the identical information about the purpose of the study like in the introductory session, according to which were interested in how mood and perceived stress tuctuated in daily life, and whether smartphones were suitable to assess their temporal trajectories. Regarding the self-portraits, we did not give any explanation on their purpose. After having sent the post-placebo-intervention self-portrait, participants received a 'Thank you' message from us. 2) Prospective expectancy only: on intervention day 1, we told participants that we were interested whether a smartphone-based intervention lasting several weeks might have a positive effect on mood and stress perception. Moreover, we explained that previous studies had demonstrated that green light and soft tones beyond acoustic detection threshold had positively affected the activity of certain brain regions, for instance, the insular lobe. We provided further details on the role of the insular lobe in the formation of unpleasant emotions and the release of stress hormones. We told participants that we assumed that daily exposure to a green picture or an inaudible sound would positively affect their mood and perceived stress in general and their ratings of emotional pictures in particular. Regarding the self-portraits, the procedures were identical to the control condition. 3) Retrospective expectancy only: initial instructions on the purpose of the study were identical to the control condition. Regarding the self-portraits, we told participants that the ohmage app would compare the emotional facial expression of the two self-portraits which might differ according to the levels of mood and perceived stress. After having taken the post-placebo-intervention self-portrait, participants were informed by the ohmage app that their picture was currently." https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full 12a) Statistical methods used to compare groups for primary and secondary outcomes NPT: When applicable, details of whether and how the clustering by care providers or centers was addressed https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full Does your paper address CONSORT subitem 12a? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "We split the four different conditions into two factors consisting of two levels each: prospective expectancy condition (yes vs. no) and retrospective expectancy condition (yes vs. no), and we entered these variables separately into the models. The variable 'intervention day' was logarithmized with base 10 and centered. Each of the two subscales of the CEQ was entered as outcome variable in separate linear mixed-effects models [33], to estimate changes in credibility or expectancy across intervention days, depending on condition. For our main analyses, we entered the following predictors into the models: i) 'intervention day' (dimensional, days 0, 1, 7, 14, 20, logarithmized with base 10 and centered), ii) 'prospective expectancy' (yes vs. no), iii) 'retrospective expectancy' (yes vs. no), as well as the interactions of 'intervention day' with 'prospective expectancy' and 'retrospective expectancy'. We entered random intercept and random slope parameters as this improved model Pt, the latter assessed based on Akaike's Information Criterion (AIC) [33], allowing time trajectories of participants to vary per participant and intervention day. With respect to our hypothesis, we were especially interested in a condition x time interaction effect (three-way interaction as condition was entered as two separate variables). We checked residual plots for linearity and normal distribution of residuals.
In additional analyses, we conducted separate linear mixed models each controlling for the effects of either 'prospective expectancy or 'retrospective expectancy'. When controlling for 'prospective expectancy', we conducted separate models for cases with 'prospective expectancy' respectively without, and the predictors i) 'intervention day' and ii) 'retrospective expectancy', as well as the interaction of 'intervention day' with 'retrospective expectancy'. Likewise, when controlling for 'retrospective expectancy', we conducted separate models for cases with 'retrospective expectancy' respectively without, and the predictors i) 'intervention day' and ii) 'prospective expectancy', as well as the interaction of 'intervention day' with 'prospective expectancy'." https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full subitem not at all important 1 2 3 4 5 essential 12b) Methods for additional analyses, such as subgroup analyses and adjusted analyses 12a-i) Imputation techniques to deal with a'rition / missing values Imputation techniques to deal with attrition / missing values: Not all participants will use the intervention/comparator as intended and attrition is typically high in ehealth trials. Specify how participants who did not use the application or dropped out from the trial were treated in the statistical analysis (a complete case analysis is strongly discouraged, and simple imputation techniques such as LOCF may also be problematic [4]).

Auswahl löschen
Does your paper address subitem 12a-i? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "For our mixed model analyses, we included all subjects of the intention-to-treat population (see Figure 2)." Does your paper address CONSORT subitem 12b? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study

RESULTS
13a) For each group, the numbers of pa"icipants who were randomly assigned, received intended treatment, and were analysed for the primary outcome NPT: The number of care providers or centers performing the intervention in each group and the number of patients treated by each care provider in each center Does your paper address subitem X26-ii?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study Meine Antwort

X26-iii) Safety and security procedures
Safety and security procedures, incl. privacy considerations, and any steps taken to reduce the likelihood or detection of harm (e.g., education and training, availability of a hotline)

Does your paper address subitem X26-iii?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full 13b) For each group, losses and exclusions a#er randomisation, together with reasons subitem not at all important 1 2 3 4 5 essential Does your paper address CONSORT subitem 13a? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "The tow of participants is presented in Figure 2, according to the Consolidated Standards of Reporting Trials (CONSORT) [42]." Does your paper address CONSORT subitem 13b? (NOTE: Preferably, this is shown in a CONSORT &ow diagram) * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "The tow of participants is presented in Figure 2, according to the Consolidated Standards of Reporting Trials (CONSORT) [42]."

13b-i) A'rition diagram
Strongly recommended: An attrition diagram (e.g., proportion of participants still logging in or using the intervention/comparator in each group plotted over time, similar to a survival curve) or other Pgures or tables demonstrating usage/dose/engagement. https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full 14a) Dates de!ning the periods of recruitment and follow-up subitem not at all important 1 2 3 4 5 essential Does your paper address subitem 13b-i?
Copy and paste relevant sections from the manuscript or cite the Pgure number if applicable (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study

Meine Antwort
Does your paper address CONSORT subitem 14a? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "The study was conducted between February and October 2015 at the Department of Psychology of the University of Basel, Switzerland." 14a-i) Indicate if critical "secular events" fell into the study period Indicate if critical "secular events" fell into the study period, e.g., signiPcant changes in Internet resources available or "changes in computer hardware or Internet delivery resources" https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full 14b) Why the trial ended or was stopped (early) 15) A table showing baseline demographic and clinical characteristics for each group NPT: When applicable, a description of care providers (case volume, qualiPcation, expertise, etc.) and centers (volume) in each group Does your paper address subitem 14a-i?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study

Meine Antwort
Does your paper address CONSORT subitem 14b? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study Not applicable.
Does your paper address CONSORT subitem 15? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "Baseline characteristics of study participants are presented in Table 1

15-i) Repo" demographics associated with digital divide issues
In ehealth trials it is particularly important to report demographics associated with digital divide issues, such as age, education, gender, social-economic status, computer/Internet/ehealth literacy of the participants, if known.
Does your paper address subitem 15-i? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "Baseline characteristics of study participants are presented in Table 1."

16-i) Repo" multiple "denominators" and provide de%nitions
Report multiple "denominators" and provide dePnitions: Report N's (and effect sizes) "across a range of study participation [and use] thresholds" [1], e.g., N exposed, N consented, N used more than x times, N used more than y weeks, N participants "used" the intervention/comparator at speciPc pre-dePned time points of interest (in absolute and relative numbers per group). Always clearly dePne "use" of the intervention.
Auswahl löschen https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full subitem not at all important 1 2 3 4 5 essential 17a) For each primary and secondary outcome, results for each group, and the estimated e&ect size and its precision (such as 95% con!dence interval) Does your paper address subitem 16-i? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study In our Tables, we included ns per group whenever applicable.

16-ii) Primary analysis should be intent-to-treat
Primary analysis should be intent-to-treat, secondary analyses could include comparing only "users", with the appropriate caveats that this is no longer a randomized sample (see 18-i).

Does your paper address subitem 16-ii?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full subitem not at all important 1 2 3 4 5 essential Does your paper address CONSORT subitem 17a? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "Descriptive statistics can be found in Table 2 and in the interaction plots of Figure   3. Results of the main mixed models are presented in Table 3." "Results from additional analyses (see Multimedia Appendix 4) suggest that the signiPcant three-way interaction was driven by two opposite two-way interactions with 95% conPdence intervals of estimates minimally overlapping." "Descriptive statistics can be found in Table 2 and in the interaction plots of Figure  4. Results of the main mixed models are presented in Table 3." with 95% conPdence intervals of estimates minimally overlapping." 17a-i) Presentation of process outcomes such as metrics of use and intensity of use In addition to primary/secondary (clinical) outcomes, the presentation of process outcomes such as metrics of use and intensity of use (dose, exposure) and their operational dePnitions is critical. This does not only refer to metrics of attrition (13-b) (often a binary variable), but also to more continuous exposure metrics such as "average session length". These must be accompanied by a technical description how a metric like a "session" is dePned (e.g., timeout after idle time) [1] (report under item 6a). https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full 17b) For binary outcomes, presentation of both absolute and relative e&ect sizes is recommended 18) Results of any other analyses pe'ormed, including subgroup analyses and adjusted analyses, distinguishing pre-speci!ed from exploratory Does your paper address subitem 17a-i?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study Not applicable.
Does your paper address CONSORT subitem 17b? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study Not applicable.
Does your paper address CONSORT subitem 18? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study

18-i) Subgroup analysis of comparing only users
A subgroup analysis of comparing only users is not uncommon in ehealth trials, but if done, it must be stressed that this is a self-selected sample and no longer an unbiased sample from a randomized trial (see 16-iii).
Does your paper address subitem 18-i?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study

Meine Antwort
Does your paper address CONSORT subitem 19? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "In cases of unexpected events, such as technical problems, the Master's students communicated via e-mail with participants. Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "To the best of our knowledge, this is the Prst empirical study investigating whether ekcacy expectancies could be successfully induced in a smartphone-based placebo mental health intervention. We found that ekcacy expectancies decreased throughout intervention days, irrespective of condition. Ekcacy expectancies decreased least in the combined expectancy and the control condition, most in the prospective expectancy only condition and the retrospective expectancy only condition."

22-ii) Highlight unanswered new questions, suggest future research
Highlight unanswered new questions, suggest future research.

Does your paper address subitem 22-ii?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full subitem not at all important 1 2 3 4 5 essential

20-i) Typical limitations in ehealth trials
Typical limitations in ehealth trials: Participants in ehealth trials are rarely blinded. Ehealth trials often look at a multiplicity of outcomes, increasing risk for a Type I error. Discuss biases due to non-use of the intervention/usability issues, biases through informed consent procedures, unexpected events.
Does your paper address subitem 20-i? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "Our results may be interpreted in lights of several limitations. First, we designed the smartphone-based intervention in line with the aim of our study to create an inert intervention. We did not focus on making the intervention particularly attractive to study participants, for instance, by integrating elements of gamiPcation [44], which may have affected the decrease in ekcacy expectancies throughout the intervention. It may be hypothesized that the time trajectories in ekcacy expectancies may differ in a study using a smartphone-based application designed to have a speciPc effect. Still, in contrast to the "law of attrition", which describes the observation of high rates of discontinuation in eHealth trials [45], we have a high completion rate, with data available for 93% of cases, which makes our Pndings relatively robust. Second, the study sample was quite homogenous, with most of the participants being female psychology students. As our sample did not consist of a clinical sample, it may rather retect subjects using smartphone for preventive purposes. Hence, Pndings may be generalizable rather to populations seeking prevention. Notable, in a clinical population, participants' desire to get an effect out of the intervention are expected to be higher than in a healthy sample, which has been found to modulate placebo analgesia in irritable bowel syndrome patients [46]. Therefore, it may even be easier to induce a digital placebo effect in a clinical sample, as compared to ours, which, however, requires further investigation. Another limitation regarding our sample is that data collection took place in the year 2015 and it would have been preferable using more recent data, particularly in a fast-emerging Peld like mHealth. However, the latency between data collection and dissemination of Pndings in our study is comparable to other https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full 21) Generalisability (external validity, applicability) of the trial !ndings NPT: External validity of the trial Pndings according to the intervention, comparators, patients, and care providers or centers involved in the trial data collection and dissemination of Pndings in our study is comparable to other relevant studies in this Peld [23,47]. Furthermore, while timely dissemination of Pndings from clinical trials would be important to base clinical decisions on best scientiPc evidence, a previous study [48] found that only 29% of completed RCTs of US academic medical centers are published within two years after study completion, indicating that, to reduce publication bias, older data needs to be disseminated, too. Nonetheless, our Pndings need imminent replication. For replication, it would also be preferable to increase the sample size, which, however, encompassed 132 participants in our main statistical analyses, and, thus, was above the median of comparable RCTs included in two recent meta-analyses ([11,12]. Third, some participants reported technical or usability problems with the ohmage app which may have led to a certain level of frustration throughout the course of the intervention, and which may have diminished ekcacy expectancies. However, as the reported frequency of technical problems with the app was low (0.6% of all cases), we do not assume that this aspect has reduced the validity of our Pndings. Fourth, as participants entered the study at different points of time, we cannot exclude that participants who had already Pnished the study might have informed others about the actual study purpose prior to study completion, which may have reduced the effect of the induction of ekcacy expectations particular in the experimental conditions. However, we speculate that this may have affected ekcacy expectancies of only few participants, because i) participants might not have remembered and passed all the details of the study design to others; ii) it might have been in the interest of most of the Psychology students to promote the study and iii) students from other Pelds than Psychology might did not systematically participate and, thus, might not have shared details of the purpose of the study. Fifth, we included only participants with access to an Android-based smartphone which limits the generalizability to iPhone and other operating systems users. However, a recent study found that personality traits (e.g. wellbeing, self-esteem, optimism, pessimism, and the Big Five) which might affect

21-i) Generalizability to other populations
Generalizability to other populations: In particular, discuss generalizability to a general Internet population, outside of a RCT setting, and general patient population, including applicability of the study results for other organizations Does your paper address subitem 21-i?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study Meine Antwort 21-ii) Discuss if there were elements in the RCT that would be di$erent in a routine application se'ing Discuss if there were elements in the RCT that would be different in a routine application setting (e.g., prompts/reminders, more human involvement, training sessions or other co-interventions) and what impact the omission of these elements could have on use, adoption, or outcomes if the intervention is applied outside of a RCT setting. Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study

Meine Antwort
Does your paper address CONSORT subitem 23? * Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study "Trial registration: ClinicalTrials.gov IdentiPer: NCT02365220. Registered February 18, 2015." Does your paper address CONSORT subitem 24? * Cite a Multimedia Appendix, other reference, or copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study The trial protocol is being described in detail in the manuscript. Further information are available from the authors.  X27-i) State the relation of the study team towards the system being evaluated In addition to the usual declaration of interests (Pnancial or otherwise), also state the relation of the study team towards the system being evaluated, i.e., state if the authors/evaluators are distinct from or identical with the developers/sponsors of the intervention.
Does your paper address subitem X27-i?
Copy and paste relevant sections from the manuscript (include quotes in quotation marks "like this" to indicate direct quotes from your manuscript), or elaborate on this item by providing additional information not in the ms, or briety explain why the item is not applicable/relevant for your study

Meine Antwort
As a result of using this checklist, did you make changes in your manuscript? * How much time did you spend on going through the checklist INCLUDING making changes in your manuscript *

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As a result of using this checklist, do you think your manuscript has improved? * We have already considered CONSORT while writing the manuscript.

Would you like to become involved in the CONSORT EHEALTH group?
This would involve for example becoming involved in participating in a workshop and writing an "Explanation and Elaboration" document

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Any other comments or questions on CONSORT EHEALTH Meine Antwort https://docs.google.com/forms/d/e/1FAIpQLSfZBSUp1bwOc_Oimq…=en_US&formkey=dGlKd2Z2Q1lNSGQ0THl1azM5MS1aWWc6MA&rm=full STOP -Save this form as PDF before you click submit To generate a record that you Plled in this form, we recommend to generate a PDF of this page (on a Mac, simply select "print" and then select "print as PDF") before you submit it.
When you submit your (revised) paper to JMIR, please upload the PDF as supplementary Ple.
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