Oku Kingsley¹, Iweka Fidelis^1,

This study was centered on the Development, Standardization and Application of Chemistry Achievement Test using the One-Parameter Logistic Model of Item Response Theory. Eight research questions and one hypothesis guided the study. The hypothesis was tested at 0.05 level of significance. The research design was instrumentation research. The Researcher developed an instrument titled “OKUKINS Chemistry Achievement Test (OKUKINS CAT) consisting of 80 items. A proportional stratified random sampling technique was used to obtain a sample of 200 students from a population of 19,082 Senior Secondary School Two (SS II) students from Delta Central Senatorial District of Delta State. The sample was further divided into two equal parts (set A and set B) representing sample A and B respectively while the original sample represent sample O. The OKUKINS CAT yielded favourable statistics under the One-Parameter Logistic Model (1-PLM) with regards to the difficulty (b) parameters and ability estimates. Analyses done using the Xcalibre 4.2 software confirmed suitable indices of b parameters as prescribed by the Xcalibre manual. Using sample O, b parameters ranged from -2.417 to +2.834. Using sample A, b parameters ranged from -2.115 to +2.293. Using sample B, the b parameters ranged from -2.138 to +2.960. The validity of the instrument was estimated using the fit statistics. The results indicated perfect fit of One-Parameter Logistic Model ( 1-PLM). Using sample O, 74 items out of the 80 items of the OKUKINS CAT fitted the 1-PLM. Using sample A, 79 items out of the 80 items of the OKUKINS CAT fitted the 1-PLM. Using sample B, all the 80 items which constitute the OKUKINS CAT fitted the 1-PLM. The study also revealed that gender has no significant influence on academic achievement in chemistry. Based on the findings, it was recommended among others that, all examination bodies such as JAMB, WAEC, NECO and NABTEB should re-visit and review their test items using IRT models since this has been recommended by the International Testing Commission.

ability estimates, difficulty parameter, standard errors of measurement, item characteristic curves, item response theory, one-parameter logistic model