Can we directly survey adherence to non-pharmaceutical interventions? : Evidence from a list experiment conducted in Germany during the early Corona pandemic

Self-reports of adherence to non-pharmaceutical interventions in surveys may be subject to social desirability bias. Existing questioning techniques to reduce bias are rarely used to monitor adherence. We conducted a list experiment to elicit truthful answers to the question whether respondents met friends or acquaintances and thus disregarded the social distancing norm. Our empirical findings are mixed. Using the list experiment, we estimate the prevalence of non-compliant behavior at 28%, whereas the estimate from a direct question is 22%. However, a more permissively phrased direct question included later in the survey yields an estimate of 47%. All three estimates vary consistently across social groups. Interestingly, only the list experiment reveals somewhat higher non-compliance rates among the highly educated compared to those with lower education, yet the variance of the list estimates is considerably higher. We conclude that the list experiment compared unfavorably to simpler direct measurements in our case.