2010 U.S. Census, 19.8% of U.S. households currently lack home-Internet access, but some individuals from these households have Internet access through smartphones. Therefore, although this sampling method does not yield a true national probability sample, it provides a diverse nonconvenience sample that is generally demographically and geographically representative of U.S. adults. The field period for data collection was September 21–29, 2010, so a large number of invitations were sent out. Because the survey was terminated when the allotted number of interviews was completed, we cannot ascertain how many individuals received invitations or the proportion of those receiving invitations that accessed the website; however, 3,756 adults accessed the website containing the National Stressful Events Survey description and survey, and 3,457 (92% cooperation rate) agreed to participate. Of those, 2,953 completed the survey (85.4% completion rate for those who agreed to participate and 78.6% completion rate for those who accessed the website). Survey data were weighted by age, sex, and race/ethnicity based on the 2010 U.S. Census. Sex, age, and race/ethnicity characteristics of the sample are included in Table 1.
