Strengths and Limitations
HOLIDAYS, SECONDARY, BLIND, EMA
The strengths and limitations of this study should be considered. Our RCTs were embedded within an ongoing cohort study that required participants to fulfill several mandatory requirements (eg, minimum Fitbit wear time and food diary logging/mo), whereas completing the EMA surveys was optional but highly encouraged, and participants may have decided to opt out of this study component. Furthermore, although our sample size was larger than that of many other EMA studies [Our pragmatic approach also meant that our secondary aim, to explore temporal changes in the response rate, was exploratory in nature. Future studies specifically designed to experimentally evaluate the effect of altering the announcement and communication strategy for each EMA burst (ie, the number of emails, SMS text messages, and push notifications that were sent to provide details of what to expect in the upcoming burst of EMA surveys) are needed. Studies evaluating the effects of other temporal variables such as holidays and key periods in the academic calendar (eg, exams) are also needed. As is typical of behavioral research, it was not possible to blind participants to their intervention condition, and we also cannot comment on whether participants received all of the EMA surveys that were sent. Furthermore, in our study, the number of EMA surveys per day varied (3-6/d), which may have lowered the response rate as participants did not know when to expect a survey. Finally, our sample consists of university students who may be especially motivated to engage in health research and therefore may not be representative of the broader population of young adults. The extent to which our findings generalize beyond this group is unclear. However, as young adults are a key population studied in EMA studies [