Monte Carlo methods were employed to assess the relative power of the paired samples t test and Wilcoxon's signed-ranks test under ten population shapes. Results of the study indicated that: (1) each of the two statistics was more powerful than the other in given situations; (2) the power advantages of the t test under normal theory were small;…

Sampling distributions for ten tests for comparing population variances in a two group design were generated for several combinations of equal and unequal sample sizes, population means, and group variances when distributional forms differed. The ten procedures included: (1) O'Brien's (OB); (2) O'Brien's with adjusted degrees of freedom; (3)…

This study used classical psychometric, latent trait, and nonparametric approaches to analyze 13- and 14-item scales of English language proficiency. Tests of English listening comprehension (dictation) and reading ("copytest") were constructed by modifying the standard dictation testing procedure to create items of text segments which…