Content validity in evaluation and policy-relevant research

It is argued that, in assessing attitudes about policy issues, the policy area can be conceptualized as a "domain of content," and standards of content validity applied. The role of content validity in policy-relevant research is illustrated in a study that contrasts the findings of two surveys concerning public opinion toward gun control. Attitudes were assessed with items from the two surveys, which focused on different aspects of the policy domain of gun control. It was found that inadequate content validity threatened inferences about the overall level of support for gun control, but not inferences about opinion differences between the sexes or between respondents of varying political affiliation. Discussion focuses on the general conditions under which inadequate content validity threatens inferences from research. Finally, it is argued that attention to content validity should enhance construct validity.