Attitudinal Polarization and Trimodal Distributions: Measurement Problems and Theoretical Implications

Objective. We present trimodality as a distributional pattern that is relevant to conceptual issues of attitudinal polarization but fits nowhere along the modality-bimodality continuum. Methods. We use simulated univariate distributions and distributions taken from the 1994 General Social Survey to investigate how commonly used measures track (or fail to track) noteworthy shirts in the distributions. Results. The kurtosis and variance are largely insensitive to important distributional differences, most importantly that between bimodality and trimodality. Conclusions. We argue that the lack of attention to trimodality and the insensitivity of commonly used measures of polarization (kurtosis in particular) to that distributional pattern create a blind spot in our thinking about polarization and can lead to basic misinterpretations of extant patterns in public opinion data.