A Megastudy of Single-Session Interventions to Challenge Depression in American Adults
Phase: NA
Conditions: Depression - Major Depressive Disorder
Sponsor: Northwestern University

 
 
 
 
 
 
 
 
 
 
 
A Megastudy of Single-Session Interventions for Depression (Includes analysis plan and 
consent form) March 8, 2025 
 
 
 
 
 
 
 
 
 
 
 
 
 

Protocol 
Design 
Participants will be randomly assigned to one of 13 conditions, with even odds of 
allocation, except that the passive control condition will have 3X odds of allocation. 
Researchers will use Qualtrics’s “evenly present elements” feature to ensure each 
condition gets a roughly equal number of participants.  
Procedure 
1. Screen. Participants will be asked to complete the Patient Health Questionnaire (9-
item, PHQ-9) to assess eligibility. Next, eligible participants will be asked to consent 
to participate in the study. 
2. Baseline session. Participants who consented will immediately begin the ﬁrst study 
session, starting with a baseline well-being questionnaire. Next, they will be 
randomly allocated to one of the 11 experimental SSI conditions, an active 
comparison SSI condition, or a passive control condition. After they complete the 
condition to which they were randomized, they will respond to some of the baseline 
measures again, as well as measures of SSI satisfaction.  
3. Follow-up. Four weeks later, participants will be invited to a follow-up survey, in 
which they will complete the baseline well-being survey again.  
Participants will be compensated directly after completing each study session. If 
participants drop out of the baseline session after randomization, they will still be invited to 
complete the follow-up survey. After each study session, participants will be offered 
access to a list of online mental health resources (see https://osf.io/wz5u6). 
Measures 
See the “Megastudy Measures” document (https://osf.io/76cfy) for information on 
measures, and the “Timepoints of megastudy measures” document (https://osf.io/hn83p) 
for information on measurement timepoints. 
To measure depressive symptoms, researchers will use the reliable and valid Patient 
Health Questionnaire (9-item). Researchers will consider a change in PHQ-9 score of 5 or 
greater to be clinically meaningful (Kroenke, 2012). To measure agency, researchers will 
use the Pathways Subscale of the State Hope Scale, a reliable and valid three-item self-
report measure of one’s perceived ability to generate plans and work toward goals. To 
measure hopelessness, researchers will use the reliable 4-item Beck Hopelessness Scale. 
Researchers will measure depression change expectancies using three items from the 

Depression Expectancies for Change scale (those with the highest item-total correlations 
in the original paper on the scale). Researchers will measure participants’ positive actions 
and thoughts (aligning with the goals of cognitive-behavioral therapy) using the Frequency 
of Actions and Thoughts Scale (FATS). Researchers will also include two multiple-choice 
questions regarding participants’ readiness to make changes toward challenging their 
depression.  
Researchers will measure how acceptable participants ﬁnd the SSIs with the Credibility / 
Expectancy Questionnaire, a few items asking if one experienced an Aha! moment during 
the SSI and how strongly the Aha! moment affected them, and a rating (out of 5 stars) of the 
intervention’s overall quality.  
References:  
Kroenke K. (2012). Enhancing the clinical utility of depression screening. CMAJ : Canadian 
Medical Association journal, 184(3), 281–282. https://doi.org/10.1503/cmaj.112004  
Interventions  
11 experimental SSIs were included for testing. The active comparison SSI is the Action 
Brings Change Project, an evidence-based SSI for depression. The passive control 
condition aims to hold attention without inﬂuencing depressive symptoms or mood (a 
three-minute video, multiple-choice questions, two-minute reading passage, three-minute 
writing exercise, all about trout). All 11 experimental SSIs, the active comparison SSI, and 
the passive control condition are available in browser (https://osf.io/nqdte) and 
downloadable versions (https://osf.io/ujbdf).  
Data Collection 
Researchers have not yet started data collection. Participants will be recruited from the 
online participant recruitment platform CloudResearch Connect and, if needed, 
CloudResearch and Proliﬁc. All study activities will take place through the online survey 
and experience management platform Qualtrics, except participants will be invited to 
participate in each study session and be compensated through their online recruitment 
platform. Participants can choose to skip any items in the study, except ones that are 
critical for an intervention to function properly. 
Hypotheses 
Primary Hypothesis  

For each SSI, we hypothesize that participants assigned to the SSI will report a different 
extent of change in depressive symptoms between baseline and four-week follow-up than 
participants assigned to the passive control condition. 
Secondary Hypotheses 
1. For each experimental SSI, researchers hypothesize that participants assigned to 
the SSI will report a different extent of change in depressive symptoms from 
baseline to four-week follow-up than participants in the active comparison 
condition. 
2. For each SSI, researchers hypothesize that participants assigned to the SSI will 
report a different extent of change in each secondary well-being outcome (agency, 
hopelessness, depression change expectancies, readiness for change, frequency of 
positive actions and thoughts) compared to participants in the passive control. 
researchers will compare change in all outcomes from baseline to four-week follow-
up, as well as from baseline to immediate post-intervention for outcomes collected 
at all three timepoints.  
3. For each experimental SSI, researchers hypothesize that participants assigned to 
the SSI will report a different extent of change in each secondary well-being 
outcome (from baseline to week four or baseline to post-intervention) than those 
assigned to the active comparison condition. 
4. For each experimental SSI, researchers hypothesize that participants will rate the 
SSI as differently acceptable than the active comparison SSI according to CEQ 
scores, star ratings, and rate of Aha! Moments. 
5. We hypothesize that participants who expect they can improve their depression 
more at baseline will show a different change in depressive symptoms from 
baseline to week four. 
6. We hypothesize that, on average, the SSIs will be more effective at improving all 
well-being outcomes (from baseline to week four or baseline to post-intervention) 
than the passive control. 
We do not make any speciﬁc hypotheses about which SSIs will be more effective or 
acceptable than others. 
 
 
 

Statistical Analysis Plan 
Inclusion criteria 
Participants will need to be at least 18 years old, be able to read and write ﬂuently in 
English, and have enough access to the internet to complete two sessions over four weeks. 
They must also score at least 10 on the PHQ-9 screen (suggesting moderate depression) 
and pass the bot check (https://osf.io/kba7v) during the screen (Kroenke et al., 2001).  
All participants who are randomized to an experimental condition (and therefore 
completed all baseline measures) will be included in analyses. If a participant begins a 
survey multiple times, researchers will only keep data from the ﬁrst time.  
Please see the measures document (https://osf.io/76cfy) and the data cleaning script 
(https://osf.io/jpk38) for details on measures and recoding. Before sharing the study data, 
researchers will remove any potentially identiﬁable information, included in written 
response items. Deviations from this pre-registration will be documented. 
References: 
Kroenke, K., Spitzer, R. L., & Williams, J. B. W. (2001). The PHQ-9. Journal of General Internal 
Medicine, 16(9), 606–613. https://doi.org/10.1046/j.1525-1497.2001.016009606.x 
Primary analysis 
Researchers will use a mixed-effects linear regression model to test if depressive 
symptoms decrease more from baseline to four-week follow-up in each of the 12 active 
conditions compared to the passive control condition. Timepoint is a three-level factor 
(i.e., baseline, post-test, and week 4 follow up). The model will include a participant 
identiﬁer as a random intercept.  
Using the “lme4” and “lmerTest” packages in R, this analysis will take this form: 
lmer(depressive_symptoms ~ timepoint * condition + (1|participant_id)) 
Using lmerTest’s default, p-values will be calculated using Satterthwaite's method for 
denominator degrees of freedom.  
Secondary analyses (matching the hypotheses above): 
1. To test if each experimental SSI changes PHQ-9 scores differently from the active 
comparison SSI, researchers will redo the main analysis, except using the active 
comparison condition as the comparator. 

2. To test if each SSI changes secondary well-being outcomes to a different extent than 
the passive control, researchers will replicate the primary analysis for each 
secondary outcome. For outcomes measured at three timepoints, researchers will 
compare baseline to each timepoint.  
3. To test if each experimental SSI changes secondary well-being outcomes to a 
different extent than the active comparison SSI, researchers will redo analysis #2, 
but instead use the active comparison SSI as the comparison condition. 
4. To test if each experimental SSI differs in acceptability from the active comparison 
SSI, researchers will conduct a linear regression model testing between-group 
differences in intervention acceptability for each acceptability outcome at each 
timepoint the outcome was collected. For these analyses, researchers will drop 
data from the passive control because it does not make sense to compare 
satisfaction with a mental health intervention to satisfaction with an educational 
program about trout. 
5. To test if participants who expect that they can change their depression more at 
baseline will show a different reduction in depressive symptoms from baseline to 
week four, researchers will run a linear mixed-effects regression model with 
depressive symptoms as the DV, timepoint, baseline depression expectancies, and 
the interaction between the two as predictors, and a participant identiﬁer nested in 
experimental condition as a random intercept. 
6. To test if, on average, the SSIs will be change each outcome differently than the 
passive control, researchers will re-run the main analysis with experimental 
condition re-coded into a two-level factor in which any of the 12 active SSIs will be 
coded as “active.” The random intercept, participant ID will be nested within 
experimental condition. For outcomes measured at three timepoints, researchers 
will compare the baseline to each timepoint 
Sensitivity analyses: 
1. Researchers will re-run the primary analysis with demographic covariates: age, 
gender, disability, race, education, relationship status, political party, employment 
status, household income, and perceived socioeconomic standing (Social Ladder). 
2. Researchers will re-run the primary analysis with demographic and baseline mental 
health covariates: age, gender, disability, race, education, relationship status, 
political party, employment status, household income, perceived socioeconomic 
standing (Social Ladder), baseline depression change expectancies, baseline 

positive actions and thoughts, baseline readiness for change, baseline agency, and 
baseline hopelessness. 
3. Researchers will test for differential attrition across conditions and by the 
interaction of condition and each covariate. If researchers ﬁnd evidence for 
differential attrition, researchers will conduct a sensitivity analysis re-running 
primary and secondary analyses accounting for differential attrition using inverse 
probability weighting. See the analysis script (https://osf.io/5eya3) for details. 
Robustness Check: Researchers will not correct for multiple hypotheses in primary and 
secondary analyses because each test of an intervention’s effect is viewed as a separate 
hypothesis. However, it might be that some statistically signiﬁcant results detected are 
false positives that occur due to testing so many hypotheses at once. To examine this 
possibility, researchers will conduct a robustness check that replicates all analyses that 
compare an outcome across many conditions correcting for multiple hypotheses using the 
Benjamini-Hochberg procedure (Benjamini & Hochberg, 1995). 
Inference Criteria: P-values will be used as the criterion for statistical signiﬁcance. Two-
sided tests will be used for all analyses. Effects of p ≤ .05 will be reported as signiﬁcant, .05 
< p ≤ .1 as marginally signiﬁcant, and p > .1 as nonsigniﬁcant.  
Missing data handling: Because participants can choose to skip items, there may be 
some missing data within outcome measures. If one’s response to a scale is missing 33% 
of its items or fewer, researchers will impute a value for each missing item using the mean 
of the other items of the scale that the participant answered. 
If an outcome scale is missing more than 33% of its items, researchers will consider the 
entire scale to be missing. In these cases, researchers will not impute missing outcome 
data because linear mixed models’ estimates for longitudinal clinical trial data are not 
improved by outcome data imputation (Chakraborty & Gu, 2009). Researchers will impute 
missing covariate data as described in the cleaning script (https://osf.io/jpk38).  
Sample Size: Researchers will aim to recruit 500 participants per intervention condition, 
except that the passive control condition will have 3X as many participants as the other 
conditions because it will improve the statistical power of analyses comparing conditions 
to the passive control. Thus, researchers aim for a total baseline sample size of n = 7,500. 
This sample size will enable us to detect change in depressive symptoms from baseline to 
follow-up between each intervention condition and the passive condition with an effect 
size smaller than Cohen’s d = 0.17, with 90% power and alpha = 0.05. This sample size will 
also allow us to detect differences in change in depressive symptoms from baseline to 
follow-up between each intervention condition smaller than d = 0.19.  

References: 
Bates, D. (2014). Fitting linear mixed-effects models using lme4. arXiv preprint 
arXiv:1406.5823. 
Benjamini, Y., & Hochberg, Y. (1995). Controlling the False Discovery Rate: A Practical and 
Powerful Approach to Multiple Testing. Journal of the Royal Statistical Society Series B: 
Statistical Methodology, 57(1), 289-300. 
Chakraborty, H., & Gu, H. (2009). A Mixed Model Approach for Intent-to-Treat Analysis in 
Longitudinal Clinical Trials with Missing Values. RTI Press. 
http://www.ncbi.nlm.nih.gov/books/NBK538904/ 
Kuznetsova, A., Brockhoff, P. B., & Christensen, R. H. B. (2017). lmerTest package: tests in 
linear mixed effects models. Journal of statistical software, 82(13). 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Consent Form 
Please read through the study consent form below and indicate if you agree to participate. 
 
Title of Research Study: A Megastudy of Single-Session Interventions to Challenge 
Depression in American Adults 
Principal Investigator: Dr. Jessica Schleider, Ph.D. 
Supported By: This research is supported by the National Institute of Mental Health and 
the Medical Social Sciences and Preventive Medicine departments at Northwestern 
University. 
Conﬂict of Interest Disclosure:  
We have no conﬂicts of interest relevant to this study to disclose. 
Key Information about this research study:  
The following is a short summary of this study to help you decide whether to be a part of 
this study. Information that is more detailed is explained later on in this form. 
• 
The purpose of this study is to compare different short programs that are intended 
to help people overcome feelings of depression. 
• 
In this session, you will be asked to answer some questions about your feelings and 
experiences, complete a short program intended to help you improve your mental 
health, and then share your thoughts on the program and answer some more 
questions about yourself. Four weeks from now, we will invite you through 
CloudResearch to complete a ﬁve-minute follow-up questionnaire about how you 
are feeling. 
• 
This session will likely take about 20 minutes and the next session will be about 5 
minutes. 
• 
The primary potential risk of participation is that the program you complete could 
make you feel worse than you do now. However, we have done our best to ensure 
that the program you complete will be helpful and not harmful. 
• 
The main beneﬁt of being in this study is a beneﬁt to society: the study’s results 
could help make programs for mental health that are more helpful in the future.  
• 
A description of this clinical trial will be available on www.ClinicalTrials.gov, as 
required by U.S. Law. This Web site will not include information that can identify you. 
At most, it will include a summary of the results. You can search this Web site at any 
time. 

Why am I being asked to take part in this research study? 
We are asking you to take part in this research study because you are an adult 18 years or 
older in the United States, your score on the measure of depression symptoms you just 
completed met criteria as “moderate” or more severe, you are ﬂuent in English, and you 
have access to the internet via a computer, tablet or smartphone. We would like your help 
to test if the programs we are studying can improve well-being and reduce feelings of 
depression. 
How many people will be in this study? 
We expect 7,500 people will participate in this research study.  
What should I know about participating in a research study? 
• 
Whether or not you take part is up to you. 
• 
You can choose not to take part. 
• 
You can agree to take part and later change your mind. 
• 
Your decision will not be held against you. 
• 
You can ask all the questions you want before you decide. 
• 
You do not have to answer any question you do not want to answer.  
What happens if I say, “Yes, I want to be in this research”? 
  
• 
You will be asked to complete two sessions: one now and one in four weeks. At 
several points in the study, you will be asked questions about yourself and how you 
are feeling. You will complete a short online program intended to help you deal with 
feelings of depression and be asked for your feedback on the program. 
• 
This session should take 20 minutes, the second session should take 5 minutes. 
• 
You will not interact with anyone during this survey or the next two surveys. You can 
complete the surveys independently at your own pace, within the time window 
allotted by CloudResearch. 
• 
The research will be carried out entirely online. 
• 
There are 13 groups of study participants in this study, and each group completes a 
different program. The group of study participants you will be assigned to will be 
chosen by chance, like ﬂipping a coin. Neither you nor the study team will choose 
which study group you are assigned to. You will have an equal chance of being 

assigned to any given group, except for the “control group”, to which you will have 
three times higher change of being assigned. 
 
Will being in this study help me in any way? 
We cannot promise any beneﬁts to you or others from your taking part in this research. 
However, possible beneﬁts include: 
• 
The program that you complete could be helpful for you, improving your well-being 
or helping you learn about yourself. At the end of the study, you will also be given 
access to other free online programs for depression that you can use as you wish.  
• 
This research can beneﬁt society and other people who struggle with their mental 
health by advancing knowledge about how to make online mental health programs 
more helpful. Once we know which programs are most (and least) helpful, we will 
do our best to share this knowledge so that others can build on our work.  
Is there any way being in this study could be bad for me? 
Possible risks include: 
It is possible that the program you complete could make you feel worse than you do. For 
example, it might make you reﬂect on negative experiences or aspects of yourself that are 
painful to think about. The program might also encourage you to make a change in your life 
that ends up being a mistake. However, the program will not expose you to more risk than 
you could reasonably be expected to face in your normal daily life. We have taken care to 
ensure the program you will test is as helpful and as harmless as possible. 
 Some of the questions in this study ask about sensitive topics that may be upsetting to 
think about, including asking about thoughts of self-harm or suicide. 
We will not be able to link your responses to you, so we will not be providing you with 
personal feedback or referrals based on your responses to questions. If you are concerned 
about your mood, please refer to the resource referral information sheet provided at the 
bottom of this document. In addition, if you would like to talk to a member of the research 
team about negative feelings you experience resulting from these questions or anything 
else in the study, please do not hesitate to reach out via the contact information, also at the 
bottom of this document. If you have been thinking about death or suicide, we encourage 
you to visit http://www.suicidepreventionlifeline.org/ or call 988. 
A possible risk for any research is that conﬁdentiality could be compromised – that is, 
people outside the study might get hold of conﬁdential study information.  We will do 
everything we can to minimize this risk, as described in more detail later in this form. For 

one, we do not ask you for any information that someone could use to identify you. We plan 
to share the data from this study publicly but we will exclude all data that could possibly be 
used to identify who participated in the study. 
What happens if I do not want to be in this research, or I change my mind later? 
Participation in research is voluntary. You can decide to participate or not to participate.  If 
you do not want to be in this study or withdraw from the study at any point, your decision 
will not affect your relationship with Northwestern University. 
 
if you just want to try out a program without being in this research study, you can reach out 
to benjamin.kaveladze@northwestern.edu and he will send you the programs you could 
have completed in the study.  
If you decide to leave this study, we will keep your data unless you disallow us to do so. You 
can write to anyone on our research team through CloudResearch or email asking us to 
destroy your data. If you say yes now, you can change your mind at any time without getting 
into any trouble. You will not have to reveal your identity to contact us because messaging 
is anonymous on CloudResearch. 
How will the researchers protect my information? 
We will use Qualtrics at Northwestern University to host our surveys. Qualtrics is a secure, 
HIPAA compliant, web-based application that collects online research data. Your data will 
be kept on a secure server at Northwestern University, accessible only to the research 
team. That is, no one other than the research team will have access to the information you 
provide. 
Who will have access to the information collected during this research study? 
Efforts will be made to limit the use and disclosure of your personal information, including 
research study records, to people who need to review this information. We cannot promise 
complete secrecy. We will not ask you for any information that could be used to identify 
you. 
There are reasons why information about you may be used or seen by other people beyond 
the research team during or after this study. Examples include: 
University officials, government officials, study funders, auditors, and the Institutional 
Review Board may need access to the study information to make sure the study is done in a 
safe and appropriate manner.   

We will publicly share the data for this study when we publish it, but we will remove any 
responses you give that could possibly reveal your identity. 
How might the information collected in this study be shared in the future? 
We will keep the information we collect about you during this research study for study 
recordkeeping. De-identiﬁed data from this study will be shared with the research 
community, with journals in which study results are published, and with databases and 
data repositories used for research. We plan to contact you again in four weeks as part of 
this research study. 
Will I be paid or given anything for taking part in this study? 
You will receive compensation electronically through CloudResearch for your participation 
in this study. If you do not complete a study session, you will not be compensated for it. You 
already earned $0.25 for answering the screening questions. You will be paid $3.00 USD for 
completing this 20-minute ﬁrst part of the study and $1.00 for completing the second part 
in four weeks. 
Who can I talk to? 
If you have questions, concerns, or complaints, you can contact the Principal Investigator 
Dr. Jessica Schleider at 917-439-1872, Dr. David Mohr at 312-503-1403, or Dr. Benjamin 
Kaveladze at 312-503-8039. 
 
If you’d like, you can access a list of mental health resources that we put together at this 
link: 
https://drive.google.com/ﬁle/d/11xAwnRJn1Lk_EL4aUzZyAWkbmojBEL_p/view?usp=sharin
g. 
 
This research has been reviewed and approved by an Institutional Review Board (“IRB”) – 
an IRB is a committee that protects the rights of people who participate in research 
studies. You may contact the IRB by phone at (312) 503-9338 or by email at 
irb@northwestern.edu if: 
Your questions, concerns, or complaints are not being answered by the research team. 
You cannot reach the research team. 
You want to talk to someone besides the research team. 

You have questions about your rights as a research participant. 
You want to get information or provide input about this research.  
If you want a copy of this consent for your records, you can print it from the screen.  
If you cannot print the consent and would like a copy for your records, contact the Principal 
Investigator with the contact information above. 
 
If you wish to participate, please click the “I Agree” button and you will be taken to the 
survey. 
If you do not wish to participate in this study, please select “I Disagree” and you will still 
receive your $0.25 payment.