Participants and procedure
The study used a two-group non-randomised controlled design with a pre-test and a post-test. The data were collected in April 2020. The participants were French-speaking volunteers who enrolled in the SPARK Resilience Programme. The intervention was delivered in a group coaching format via synchronous video conferencing using Zoom software over eight 90-minute sessions spanning four weeks. The sessions included a combination of teaching, whole-group interactions, questioning, using voice and chat functionalities, quizzes, small virtual group discussions, peer coaching, guided mindfulness exercises, and non-mandatory homework. The SPARK sessions were conducted by two trainers with postgraduate degrees in psychology (MSc and PhD, respectively), background in positive and organizational psychology, and extensive experience in group facilitation and resilience work.The participants were recruited from among the individuals who had registered for a free pilot trial of the SPARK Resilience Programme for French-speaking adults scheduled to take place in April 2020. The training was advertised using mailing lists and positive psychology-themed websites in March. Although the advertisements mainly targeted working professionals, students were also allowed to register. Once it became clear that the number of potential participants would exceed the limitations imposed by the Zoom platform (The week before the April wave was due to start, all SPARK participants from both groups received an email invitation to take part in a research study of psychological factors and dynamics of resilience in the context of the COVID-19 pandemic. The study involved completing a set of online questionnaires twice, at a one-month interval. Those who opted to take part in the study received a link to the pre-test questionnaire immediately and another link to the post-test questionnaire one month later. Participation in the study was voluntary and was not a condition for participation in the SPARK programme itself. The trainers had no information about the study participation or the responses provided by specific individuals. To ensure a realistic representation of SPARK programme participants, the study did not use any specific exclusion criteria. The research was conducted in accordance with the Declaration of Helsinki. Informed consent in an electronic form was obtained from all participants. The study protocol was approved by the HSE University Research Ethics Committee.The number of questionnaires collected was 390 for the pre-test (177 in the intervention group and 213 in the control group) and 232 for the post-test (140 in the intervention group and 92 in the control group). For the present study, we used the data of participants who completed both the pre-test and the post-test and whose questionnaires could be matched based on the identifiers they provided. The resulting sample included 101 participants in the intervention group and 86 in the control group (three control group participants provided incomplete questionnaires; we report the effective sample size for each analysis).The participants were mostly female (87.1%) and ranged in age from 20 to 76 (