Abstract:
The purpose of this study was to estimate multiple sources of variation and score dependability in Economics essay test using generalizability theory. The study adopted fully crossed research design. The population for the study comprised one thousand eight hundred and thirty five (1835) SSII Economics students in the 47 public secondary schools in Aguata education zone of Anambra State. A sample size of 328 SSII Economics students was used for the study. The sample was obtained using purposive sampling technique. Economics Essay Test (EET) was used to collect data for this study. The instrument (EET) was validated by experts in Social Science Education (Economics Unit) and Science Education (Measurement and Evaluation), Faculty of Education, University of Nigeria, Nsukka. The instrument was trial tested on a sample of twenty five (25) SSII Economics students in Nsukka education zone to determine its internal consistency and reliability coefficient of 0.85 was obtained using Kendall’ coefficient of concordance. The data obtained for the study were analyzed using a computer program (EduG version 6.1-e) specifically designed for generalizability theory to answer the research questions. The findings of the study revealed that: the largest variance component recorded was the residual (that is, SIR interaction) component which accounts for 77.6 % of the total variance in the G-study followed by student [σ2 (S)] component which account for 15.1 % of the total variance. The third largest variance component was that of SR followed by the rater (R). Variances for item [σ2 (I)], student-by-rater [σ2 (SR)] and the item-by-rater interaction effect [σ2 (IR)] were found to be zero (0.0); increasing the number of items produces a more generalizability and reliability coefficient than increasing the number of raters; the relative and absolute error variance influencing the facets and their interactions were found to be 0.3590 and 0.3642 respectively. Based on the findings, it was recommended among others that test item writers should endeavour to increase the number of items of their questions to produce a better reliability and generalizability coefficient of the items.
