Study Design and Procedure
MAY, BLIND
From January to December 2021, we conducted a 3-armed randomized controlled trial with 2 IGs and a waitlist CG, with equal randomization across the groups. Because conducting the group training sessions required a lot of resources, there were 2 passes: one cohort (ie, web-based IG [IG-ON], blended IG [IG-BL], and CG) started in January, and the other started in May. The participants were aware of differing training start dates but were unaware of their assignment to one of the IGs or the waitlist CG (ie, single blind). However, they could not be blinded to their allocation to the web-based or blended training format because of the nature of format differences.To recruit participants, we used a snowball sampling approach, email distribution lists, newsletters, professional networking websites, and magazine articles. We promoted the study as free training to help workers cope with the challenges of FWDs. The participants were aware that they would be randomly assigned to either web-based or blended training. The participants confirmed that they met the eligibility criteria (ie, they were at least 18 age years old, their jobs allowed them some flexibility, and they were willing to complete the training and all questionnaires) during registration via a website. We did not limit participation to a specific type of FWDs because FWDs can include different levels of flexibility, such as working in an office with flexible hours, telecommuting part time, or working remotely all the time. To complete the registration, the participants were required to sign an informed consent form and a data protection form. That is, the participants were provided with detailed study and privacy information and confirmed that they had read, understood, and accepted the information by checking a box. Because the registration process required internet access and a valid email address, computer and internet literacy were implied as eligibility criteria.The participants completed a baseline (T0) questionnaire before we randomly allocated them to the waitlist CG, IG-ON, or IG-BL. As the dates for the blended training group sessions were set, the randomization of the participants into all 3 groups would have most likely resulted in higher attrition, as participants assigned to a specific blended group session might not have been able to attend. Hence, all the participants provided their time preferences for group sessions, knowing that these preferences would be relevant only when randomized to this particular group, when they registered. In an Excel (Microsoft Corporation) spreadsheet, a member of the author team generated a list of an equal number of group assignments and random numbers between 0 and 1. These were then sorted, resulting in a randomized list of group assignments, which were then matched to the list of participants. The participants who indicated that they did not have time on any of the available dates for the group sessions were randomized only between the IG-ON and waitlist CG (158/575, 27.5%). All other participants were randomized among all 3 experimental conditions (417/575, 72.5%).After the IGs completed the training, we sent the postintervention time point (T1) questionnaire to all the participants. Four weeks later, we sent them the 4-week follow-up (T2) questionnaire. Then, the waitlist CG could access the training. Furthermore, we sent the IGs a 6-month follow-up (T3) questionnaire. We asked the participants to complete the questionnaires within 2 weeks. As an incentive for active participation, we offered participation certificates and information about project results.