Replication Data for: Comparing Three Measures of Legislative Professionalism

We evaluate three measures of state legislative professionalism: Squire’s (1992) index that measures professionalism relative to the US House, Bowen and Greene’s (2014b) two dimensional scaling, and legislative operating expenditures per member, an older measure that remains in occasional use. Replications of 18 recent articles show that these three measures regularly produce significantly different estimates of the effect of professionalism, particularly in longitudinal analysis; when they do, the choice of measure often affects whether other central variables retain a significant relationship with the dependent variable. These divergent results appear to reflect differences among these measures in terms of missingness, vulnerability to outliers, measurement of session length, and whether to benchmark to the US House. Researchers seeking a general indicator of professionalism should consider these differences when choosing an appropriate measure.