An experimental validation method for questioning techniques that assess sensitive issues

Studies addressing sensitive issues often yield distorted prevalence estimates due to socially desirable responding. Several techniques have been proposed to reduce this bias, including indirect questioning, psychophysiological lie detection, and bogus pipeline procedures. However, the increase in resources required by these techniques is warranted only if there is a substantial increase in validity as compared to direct questions. Convincing demonstration of superior validity necessitates the availability of a criterion reflecting the "true" prevalence of a sensitive attribute. Unfortunately, such criteria are notoriously difficult to obtain, which is why validation studies often proceed indirectly by simply comparing estimates obtained with different methods. Comparative validation studies, however, provide weak evidence only since the exact increase in validity (if any) remains unknown. To remedy this problem, we propose a simple method that allows for measuring the "true" prevalence of a sensitive behavior experimentally. The basic idea is to elicit normatively problematic behavior in a way that ensures conclusive knowledge of the prevalence rate of this behavior. This prevalence measure can then serve as an external validation criterion in a second step. An empirical demonstration of this method is provided.