Abstract
Studies of ion motion in glasses are divided between analyses based upon the Kohlrausch description of the electric modulus and the Jonscher power law description of the ac conductivity. It was recently demonstrated that the latter approach suffers from a so-called `window effect': the power law exponent obtained from optimized curve fitting is affected by variations in the accessible frequency range of the experiment. In the present work, a statistical treatment of the curve fitting is conducted which reveals that the changes in the exponent are accompanied by increases in the error in determining the exponent. Although deviations are evident between the data and the fit, the observed change in the exponent generally remains within the error of determination and renders the window effect statistically irrelevant.