The study investigates indices of ethnic diversity and their underlying theoretical models for method effects due to differences in operationalization. It adapts the methodology of Multitrait-Multimethod analysis to the field of comparative research. While approaches for checking construct validity or method bias are common in psychology and educational research, they are rarely applied in other social science disciplines such as economics and political science. We find that measures of polarization show considerable method effects which call their empirical utilization for multivariate modelling into question. We conclude that improved overall measures, which are based on a theoretical augmentation of a construct’s measurement instrument, do not necessarily lead to improved results, neither on the measurement level nor for hypothesis testing.
