Comment on “Intellectual Differences in Five-Year-Old Underprivileged Girls and Boys with and without Pre-Kindergarten School Experience”:

Smith (1968) examined the intellectual differences between children who had participated in an 11-mo. pre-kindererren program and children who had no such experience. Two intelligence tests, Stanford-Binet and the Peabody Picture Vocabulary Test, were used to assess intellectual differences. It was found that the children who had participated in the pre-kindergarten program performed significantly better than the children who had not participated. It was further shown that this difference was due solely to the high achievement of the pre-kindergarten program girls since the pre-kindergarten boys did no better than the no pre-kindergarten boys. Smith (1968) suggests hat chere may be an interaction between the higher degree of psycho-social readiness among the girls and a curriculum adapted to that readiness. The experimental design used by Smith (1968) is an ex port facto design (Campbell & Stanley, 1963; Kerlinger, 1964). "Ex post facro research may be defined as that research in which the independent variable or variables have already occurred and in which the researcher starts with the observation of a dependent variable or variables" (Kerlinger, 1964. p. 360). Since a posttest is given after an experimental treatment and the control group is assigned a posteori, the control group enters the design only at the posttest. Though the author states that the groups are "comparable," this comparability is open to question. The control group are children entering a Headstart program. They are the same age as the experimental group. However, the author does not reveal on what basis the pre-kindergarten program children were chosen and why the control group had to wait 11 mo. before they could begin a Headstart program. Obviously, some children in the neighborhood entered neither group, thus the selection proceedings seem to be important. Differences between the groups are suggested by the fact that 12 of the control group children were "untestable." Since the author does not report a comparable number of untestable pre-kindergarten children, questions may arise about differences between the groups other than the treatment program. A major problem with ex post facro research is that ". . . when assignment is not random, there is always a loophole for other variables to crawl through" (Kerlinger, 1964, p. 363). A much better design would have been to assign randomly half of the children eligible for the pre-kindergarten program to the program and allow the nonchosen children to serve as the control group. The criteria of intellectual achievement used were the Stanford-Binet Intelligence Test, Form L-M, and the Peabody Picture Vocabulary Test (PPVT). Though it is commendable that the researcher used at least mro criteria, it is regrettable that they are so alike. The PPVT is a test of the child's ability to match words with appropriate pictures. The Stanford-Binet is highly loaded with this verbal factor especially at these low ages. Therefore, it is possible that instead of getting at the breadth of intellectual development, these two tests may be examining very similar intellectual abilities. Since both criteria center on one facet of children's intelligence, one wonders if rhese skills were taught in the program. While it is hoped that intelligence tests have predictive