Background: Survey self-reports of health status, symptoms (pain and fatigue), and life satisfaction often serve as outcomes in clinical trials. Prior studies have shown, however, that such reports can be subject to context effects, which could threaten their validity.
Research Design: We examined the impact of 2 context effects: the effect of the reporting period associated with a question (No Period Specified; Last Month; Right Now) and the effect of whom the respondent compared themselves to in answering a question (None Specified; Compared with Others in the US; Compared with 20-Year-Olds).
Results: One thousand four hundred seventy-one community adults aged 20 through 70 years, who were members of an internet panel, responded to 1 of 9 questionnaires formed by crossing the 2 context variables. A significant effect of Reporting Period was observed indicating that higher levels of Pain and Fatigue were associated with the 1-Month reporting period. When no reporting period was specified, symptom levels were equivalent to the Right Now levels of symptoms. Reporting Period had no effect on the other outcomes. Educational level did not interact with these main effects, with 1 exception. None of the predicted effects were found for Comparison Group, although Pain was significantly associated with this factor.
Conclusions: Reporting period in survey questions is a factor that influences responses and should be considered by survey researchers in their study designs.