Reliable component analysis of the Stanford-Binet: Fourth Edition for 2- to 6-year-olds.

Reliable component analysis (RCA) was conducted on the Stanford-Binet: Fourth Edition subtests for 2- to 6-year-olds using the standardization sample. Scores were derived through RCA to assess the Verbal Comprehension and Non-Verbal Reasoning factors suggested for children in this age range. The scores derived through RCA had greater discriminant validity than did equally weighted scores, whose high intercorrelations preclude effective discrimination or incremental validity. The difference scores derived through RCA were compared with equally weighted difference scores in terms of reliability and three types of standard error. Differences between RCA scores were more reliable than were equally weighted differences. The more reliable differences resulted in more precise confidence intervals and more powerful significance tests.