Reliability, item difficulty and discrimination indices of science test items in commercial test papers and their correlation to students KCPE performance in science in Limuru Subcounty.
The study was carried out to establish the factors influencing the reliability, item difficulty and discrimination indices of science test items in commercial test papers and their correlation to students KCPE performance in science in Limuru Sub-County, Kiambu County in Kenya. The study involved 200 class eight students selected using stratified random sampling from three public primary schools, 39 teachers teaching science in class eight in public primary schools in Limuru sub-county. A descriptive survey research design was applied. Data was collected through questionnaires and sample science commercial test papers administered to the students. Data collected via the sample commercial test papers was analysed first using Ms Excel, then together with the data from the questionnaires analysed using SPSS and the frequency distribution was then described. The findings of the study revealed that test duration, test quality, teacher’s; training on test construction, professional qualification, teaching experience, workload ,number of test items objectives, intended purpose of the test, testwiseness have an effect on the reliability, difficulty and discrimination indices. Other factors such as teacher and student gender, parental assistance and educational level, family type and socio- economic status have a varying influence on the student performance in summative evaluation. The teachers training on test development was seen as the main factor that would determine the quality of commercial test papers as flawed items would be moderated to come up with an almost perfect test paper. It was concluded that the commercial science test paper used in formative assessment are generally of good quality. The study recommended that science teachers should attend in- service training on test development and analysis to enhance their competency in verifying the quality of commercial test papers.