Estimation of effect size in a meta-analysis of series of validity studies on matriculation examinations in Nigeria

Abstract

The study formulated an algebraic path from the series of studies meta- analyzed on the validity of the
University Matriculation Examination (UME) in Nigeria; in order to obtain a unique and common metrics with a
view of making the results to convey the same interpretation. The study determined both the individual and
overall effect sizes of 30 empirical studies. It also established the significant difference, in the probability levels
and the effect sizes of the selected empirical studies. The study design is descriptive and involved the
integration of correlation co-efficient between two variables. The measure of effect size estimate of each of the
studies was based on Pearson’s product moment indicator using the conversion process extracted from the
works of Rosenthal (1984), Glass and Stanley (1970). The results revealed a high effect size of 0.78 and low
effect size of 0.03. The empirical studies were not significantly different in terms of their probability levels (x2
=
2.680, p > 0.05) but were significantly different in terms of their effect sizes (x2
= 1444.97, p < 0.05). This study
concluded that there was no statistical linear trend in terms of effect sizes across this set of studies and that the
heterogeneity of the effect sizes referred to fluctuation from the average of the group. The calculated effect size
did not represent adequately the outcome of all independent study, hence an indication of moderator variables
operating within the studies.