Application of Generalizability Theory in Estimating Variance Components in Senior Secondary School Certificate Examination Physics Essay Questions

Abstract

Application of generalizability theory in estimating variance components in senior secondary school certificate examination physics essay questions investigating the sources of error variance in 2019 senior secondary school certificate examination physics essay question. The design is two facet fully crossed G–study and D–study. The population is made up of one thousand, seven hundred and sixty-seven (1,767) senior secondary three (SS3) students in Obio/Akpor Local Government Area of Rivers State. Multistage sampling technique was used; simple random sampling technique and purposive sampling technique were used to select (10) senior secondary schools out of twenty-five senior secondary schools. Taro Yamane formula is applied to estimate the sample size of one hundred and sixty-seven (150) Senior Secondary three Students (SS3) from the population and the west African examination council (WASSCE 2019) physics questions was administered to the students in their various schools. Instrument for data collection 2019 May/June physics essay questions of west African senior school certificate examination (WASSCE), each item is rated on 10 points marking scheme which was adapted by the raters. The data collected was analyzed using a computer software SPSS through General linear model under Variance components MINQUE method. The result shows that student is the highest contribution of measurement error (?2si= 1.030) followed by item(?2i =.851); followed by rater (?2i.=.016); the interaction effect of the variance component shows that student*item (?2si = 2.957) interacted more and better followed by item*rater (?2ir = .036) and item*student (?2is = .024) while student*item*rater (?2sir = -2.868) which is equal to zero. The interaction effect of variance component interacted very high among students and item (?2si). The estimation of G and D study reliability coefficient which indicates that; the universe score 1.030, Relative error variance 2.981, Absolute error variance 4.878, G-study coefficient 0.26 and Index of dependability 0.17 were obtained from the score. The index of dependability is very low hence the questions were difficult. West African examination council (WAEC) should have a unit of psychometricians to verify their essay questions to establish if it has good index of dependability before sending it out for use. West African examination council (WAEC) should use generalizability theory for reliability test of all their essay questions before storing in their item banks to reduce the difficulty level of their items.