ABSTRACT
For example, Adey and Shayer (1990), Table III, reporting a two-year intervention study, cite for the boys in the experimental group, initially 12 years of age, a mean gain of 1.16 levels on Piagetian tests, compared with 0.27 levels for the controls over the same period (t=5.0, df=117, p<.01). Such information is usually the end of the data analysis in the psychological literature, yet it leaves unanswered three important questions. Quantitatively, where did the control and experimental groups range at pre-test in relation to the child population as a whole? What would the expected change have been over the two-year period for both groups, i.e. is the value of 0.27 levels gain for the controls typical of boys’ development over this age range? Lastly, given that the difference between experimentals and controls is statistically significant, how important, quantitatively and qualitatively, might this gain be for the experimental students’ learning?
