A method for medical screening is adapted to differential item functioning (DIF). Its essential elements are explicit declarations of the level of DIF that is acceptable and of the loss function that quantifies the consequences of the two kinds of inappropriate classification of an item. Instead of a single level and a single function, sets of…

Distributions are the basis for an enormous amount of theoretical and applied work in statistics. While there are formal definitions of distributions and many formulas to characterize them, it is important that students at first get a clear introduction to this basic concept. For many of them, neither words nor formulas can match the power of a…

To modify least squares estimators so that outliers arising from heavy-tailed distributions will have less influence, a robust coefficient of kurtosis, which avoids the quartic effect, is described. Aspects of Pearson's and Fisher's kurtosis coefficients are compared in the procedure. (Author/CM)