A type of interaction of two active groups is considered, in which the opposition of each group increases as the success of the other increases. Some possible applications of this situation are discussed.

The graphic item-counter is described and its use as a statistical device is explained. Procedures are presented for obtaining Pearson product-moment correlations by means of the graphic item-counter.

In this note are presented facilitating tables for the estimation of the standard error of a tetrachoric r and also tables providing significant and very significant tetrachoric coefficients for various sizes of samples and various combinations of proportions in the dichotomized distributions.

Tests of auditory function in the fields of pitch, loudness, quality (timbre), and time, auditory analysis, synthesis, and memory, together with age, intelligence, and four tests of visual memory, were studied factorially. The subjects were 200 high-school students. The intercorrelations were factored to nine factors by a modification of the centroid technique and rotated to an oblique simple structure. No general auditory factor appeared. Instead there appeared group factors tentatively identified as pitch-quality discrimination, loudness discrimination, “auditory integral for perceptual mass,” auditory resistance (synthesis and analysis), speed of closure, auditory span formation, memory span (auditory and visual), memory or incidental closure and an unidentifiable residual plane. The average intercorrelation among the primary vectors was low, only one intercorrelation being greater than .34. A number of queries are answered by the interpretation of the results.

The Lexis Ratio is discussed in its application to distributions of test scores where the items of the test can be assumed to be of equal difficulty. The ratio indicates the extent to which inter-individual variation operates as a source of the variance. The concept is related to the Lexis, Bernoulli, and Poisson distributions and illustrated by urn schemata. The Ratio is applied to the scores of 560 university freshmen on the Robinson Reading Test. The relation of the Lexis Ratio to the Kuder-Richardson estimation of reliability is also discussed and the latter authors' case IV is rewritten explicitly in terms of the Ratio.

Scoring keys, based upon unit weights, were made up for fourteen occupations of the Strong Vocational Interest Blank for Women. The study here presented of scores obtained in using these keys, in comparison with scores obtained from Dr. Strong's keys, indicates, for 551 women at the University of Rochester, that the new, unit-weighted keys are valid for all practical purposes and make possible a great saving in scoring time.