Gerson 2013 (study 1).

Methods	Study design: RCT, according to authors; but (systematic) non‐random approach: alternation Study grouping: parallel group Unit of randomisation: individuals Power (power & sample size calculation, level of power achieved): A power analysis using the G*Power 3 program indicated that power was low for a medium effect size with 28 participants (f2 = 0.32 for a multiple linear regression with 3 predictors and f = 0.25 for an analysis of covariance); preliminary study (findings should be interpreted cautiously given number of variables and very small sample size) Imputation of missing data: not specified; per‐protocol analysis (only participants who completed treatment in both groups)
Participants	Country: USA Setting: university, psychology lab Age: mean = 19.9 (SD = 2.17) years; range = 18 ‐ 26 years Sample size (randomised): 33 Sex: 20 women, 13 men Comorbidity (mean (SD) of respective measures in indicated, if available) at baseline: depression (BDI‐II)): IG: 7.88 (3.50), CG: 14.00 (7.94) Population description: undergraduates at a small, private university in southern California Inclusion criteria: not specified Exclusion criteria: not specified Attrition (withdrawals and exclusions): attrition of 5 participants (IG: 1, CG: 4) Reasons for missing data: not specified
Interventions	Intervention: Program for Accelerated Thriving and Health (PATH) (n = 16) delivery: face‐to‐face; group sessions (6 or fewer participants); PowerPoint slides, small‐group discussions; handouts at end of session 1 and beginning of session 2 providers: delivered by nonclinical personnel with minimal training; 3 group leaders selected for their interest in participating in a psychology research team (undergraduate seniors who had completed a year‐long course in research methods); training: reviewing scripts and handouts and participating in approximately 1 hour of discussion with 1 of the principal investigators about key elements of the programme; PI available between meetings to address any questions/concerns that arose from group sessions; 1 male, 2 female group leaders; informal presentation style duration of treatment period and timing: 3 x 60‐ to 90‐minute sessions/meetings over approximately 3 weeks description: focus on building an adaptive explanatory style in undergraduates each meeting: presents scripted lecture about the relevance and components of pessimistic, optimistic, and personal control explanatory styles, accompanied by colourful PowerPoint slides and interspersed with small‐group discussions of thought questions distributed in 2 handouts SESSION 1: study title; (examples of stressful events) importance of building resilience to stress: self‐perpetuating cycle between feeling overwhelmed and responding maladaptively Ellis’ A‐B‐C (Activating event, Belief, Consequences) model and impact of cognitions on feelings and behaviours importance of perspective and explanatory style explanatory style and its dimensions: internality, stability, and globality dangers of negative expectations: self‐fulfilling prophecy with own and others’ belief pessimistic explanatory style: Internal, stable, and global attributions for negative events negative impact of a pessimistic style: self‐fulfilling prophecy negative impact of a pessimistic style: self‐perpetuating cycle; (handout 1) SESSION 2: study title (handout 1) dimensions of explanatory style: review importance of positive expectations: self‐fulfilling prophecy getting perspective: considering worst, best, and realistic outcomes de‐catastrophising: maintaining specificity regarding negative events considering best possible outcomes being realistic: considering likely outcomes and their positive elements getting perspective: review (examples) pessimistic and optimistic explanatory styles and their importance in A‐B‐C model personal control explanatory style (handout 2) SESSION 3: study title pessimistic, optimistic, and personal control explanatory styles: review benefits of taking personal responsibility and active skill‐building; (handout 2) getting perspective: review comparison of pessimistic, optimistic, and personal control explanatory styles importance of active, assertive problem‐solving process of active problem‐solving: identifying goals and realistic possibilities, taking action, and evaluating outcomes HANDOUTS: presented characters’ responses to 7 complex negative situations handout 1: participants asked to analyse each response in terms of uses of internality, stability, and globality, and then to offer an optimally constructive response; group leaders guide discussion with the assistance of a response key handout 2: presents 7 brief negative scenarios for practising applications of pessimistic, optimistic, and personal control explanatory style compliance: not specified integrity of delivery: not specified economic information: study participation credit for psychology courses, opportunity to learn about managing stress, and summary of findings theoretical basis: literature on optimism and optimistic style (Peterson 2000); concept of thriving (Carver 1998); expectations regarding the adaptiveness of optimistic and personal control explanatory styles formed the basis for the programme’s content Control: wait‐list control (n = 17) compliance: not specified economic information: study participation credit for psychology courses, opportunity to learn about managing stress, and summary of findings
Outcomes	Outcomes collected and reported: thriving/resilience ‐ CD‐RISC‐10 optimism/optimistic explanatory style ‐ ASQ personal control explanatory style ‐ ASQ depression ‐ BDI‐II Time points measured and reported: 1) pre‐intervention; 2) post‐intervention; 3) 3‐week follow‐up (follow‐up only for IG; post‐intervention for CG which also receives intervention after waiting period) Adverse events: not specified
Notes	Contact with authors: We contacted the authors for the means and SDs for the outcomes in both groups at each of the 3 time points and received the response that data for study 1 appeared to be corrupted (Gerson 2018b [pers comm]). We also asked for the potential inclusion of healthcare students in the sample, but received no response to this inquiry Study start/end date: not specified Funding source: supported in part by a Summer Undergraduate Research Fellowship provided by the Office for Undergraduate Research of California Lutheran University Declaration of interest: not specified Ethical approval needed/obtained for study: approved by the university’s IRB Comments by study authors: not relevant Miscellaneous outcomes by the review authors: for study 1, unclear if psychology students were included in the study Correspondence: Marylie W. Gerson; Department of Psychology, California Lutheran University, 60 W. Olsen Road, mail code 3800, Thousand Oaks, CA 91360, USA; mgerson@callutheran.edu