Using Generalizability Theory to Investigate the Reliability of Scores Assigned to Students in English Language Examination in Nigeria

Abstract

The study investigated the reliability of scores assigned to students in English language in National ExaminationsCouncil (NECO). The population consisted of all the students who sat for NECO Senior School CertificateExamination (SSCE) in 2017 in Nigeria. A sample of 311,138 was selected using the proportionate stratifiedsampling technique. The Optical Marks Record (OMR) sheet containing the responses of the examinees was theinstrument for the study. The data was analyzed using lme4 package of R language and environment for statisticalcomputing, factor analysis and Tucker index of factor congruence. The psychometric properties of the data weredetermined by estimating the generalizability (g) coefficient, phi (Φ) coefficient and construct validity. Theresults indicated the g-coefficient to be 0.90 and Φ coefficient as 0.87, which is an indication of high reliabilityof scores. The result also showed that a decrease in the number of the items resulted in a decrease in both g- andphi coefficients in D-study. The construct validity of 0.99 obtained from the result affirms the credibility of theitems. Hence, it was concluded that the scores were dependable and generalizable.