The influence of political ideology on DIT scores: fact or artifact?

Concern about the validity of the DIT and Fisher and Sweeney’s measurement of conservative, moderate and liberal political orientation using a seven-point Likert scale motivates our study. We perform two experiments to investigate these interrelated issues. First, we assess the degree to which 569 undergraduate students’ political orientation as measured by a seven-point Likert scale associates with their corresponding political orientation as measured by a ninepoint Likert scale. We find differences in categorization of subjects depending upon scale used, suggesting problems with the sampling distribution arise when a seven-point Likert scale is used for categorizing subjects. Second, we measure 115 students’ political orientation utilizing a nine-point Likert scale to assess Fisher and Sweeney’s findings. Our results suggest that Fisher and Sweeney’s findings may relate to their using a seven-point Likert scale in measuring political orientation rather than a flaw in the DIT’s validity resulting from an embedded political ideology.