Measures of State Capacity: Same Same, but Different?

This study provides a systematic comparative analysis of seven established cross-national measures of state capacity by focusing on three measurement issues: validity, interchangeability, and rating discrepancy. The author finds that the association and convergent validity of the measures is high, but the interchangeability of the measures is low. Through the weak external validity of three replicated longitudinal studies the author demonstrates that statistical differences in measures can have considerable consequences for empirical results. The cause of these somewhat counterpoising findings lies in strikingly high rating discrepancy within some individual countries. The author finds that this rating discrepancy depends systematically on the level of state capacity. No measure of state capacity seems to be clearly superior to others, but future studies should ensure that a given definition of state capacity matches with the chosen measure and should make clear whether the findings are generalizable or not.