A Nonparametric Coefficient Of Internal Consistency

This paper discusses a frequency based, nonparametric measure of internal test consistency, referred to herein as coefficient alpha_τ, which allows facile measurement of the significance of differences in internal consistency between tests, administrations, or scoring methods. It also permits analysis of psychological tests containing items with discrete categories of response, yielding nominal scale data. Use of alpha_τ encourages flexibility in test construction, since multiple dimensions can be incorporated into individual test items.