A jack knife is a pocket knife that is put to many tasks, because it's ready to hand. Often there could be a better tool for the job, such as a screwdriver, a scraper, or a can-opener, but these are not usually pocket items. In statistical terms, the expression implies making do with what's available. Another simile, of an extreme situation, is…

Three commonly used measures of segregation (index of dissimilarity, p* interaction probabilities, and the correlation ratio) reflect three conceptually distinct aspects of racial residential segregation. The results of empirical studies will depend on the measure chosen. (Author/KH)

The contributions of school classification--regular or educable mentally retarded (EMR)--sex, and ethnic status to domain scores from the Public School Version of the Adaptive Behavior Scale were investigated. Part One measures the development of personal independence in daily living, while Part Two measures maladaptive behavior related to…