Tests the hypothesis that the Mueller-Lyer illusion will be less strong when an observer is distant from figures than when he is close, and presents results that do not confirm the hypothesis. (RW)

Two multivariate probability distributions, a generalized beta distribution and a generalized F distribution, are derived. Formulas for the moments of these distributions are given and an example of the bivariate generalized beta is presented. (Author/JKS)

Research on Piaget's four stages of cognitive development has shown that although nearly everyone passes through sensorimotor, preoperational, and concrete operational stages, most do not reach the stage of formal operations. Those people who do attain formal operations seem to have a curiosity factor not operative in those who don't. (Author/BRR)

An empirical study of the power of the F test in normal populations with variances proportional to the cell means is reported. The results indicate that the power of the test can be approximated by the noncentral F distribution with a modified parameter of noncentrality. (Author/CM)

Power and stability of Type I error rates are investigated for the Box-Scheffe test of homogeneity of variance with varying subsample sizes under conditions of normality and nonnormality. The test is shown to be robust to violation of the normality assumption when sampling is from a leptokurtic population. (Author/GK)

Guilford's average interrater correlation coefficient is shown to be related to the Friedman Rank Sum statistic. Under the null hypothesis of zero correlation, the resultant distribution is known and the hypothesis can be tested. Large sample and tied score cases are also considered. An example from Guilford (1954) is presented. (Author)

The F-distribution approximation suggested by Dixon was investigated at various combinations of alpha and degrees of freedom. Tabled values were compared with values computed utilizing the suggested formula. (Author/GSK)

The robustness of hypothesis tests for the correlation coefficient under varying conditions is discussed. The effects of violations of the assumptions of linearity, homoscedasticity, and kurtosis are examined. (JKS)

The coefficient of congruence is a quantitative measure of the similarity of factor structures for different samples of subjects. This paper is intended to inform interested readers of the availability of a computer program capable of computing coefficients of congruence of factor structures. (Author)

This program generates maximum likelihood estimates of the parameters of a mixture of two normal distributions and tests the significance of the mixture hypothesis against that of a single normal distribution. (Author)

Methods to compare population means in the univariate case and population mean vectors in the multivariate case are presented in terms of hypotheses tested by various procedures. Tests relevant to each hypothesis are described and compared in terms of maximizing power while controlling Type I error rates over the widest variety of conditions. (SLD)