The present study was on comparative analysis of reliability estimates of assessment methods by teachers in secondary schools in Port Harcourt Metropolis. Three objectives and research questions guided the study. Comparative research design was adopted in the study. The population of the study consisted of 3,340 SS2 students drawn across public schools in Port Harcourt metropolis. A sample of 100 students drawn across 10 schools in the area with the help of multi-stage sampling process was used in the study. The researcher developed two forms multiple-choice test as measuring instruments. The first was a 60 item “Formative Assessment Test” (FAT) while the second was a 50 item “Summative Assessment Test” (SAT). The FAT was administered on the respondents during the course of the instruction within the term while SAT was administered at the end of the third term as part of the promotional examinations. Test blueprint was adopted to ensure that the two instruments have content validity while factor analysis was used in determining the construct validity. Administrations of the instruments were done face to face in the class with the help of the classroom teachers. Data analysis method included KR20 , split-half and test retest methods of reliabilities. For the test-retest, the researchers repeated the process for both the formative (FAT) and summative test (SAT) after a period of two weeks interval. Result of the study showed that when KR20 was used, summative assessment had higher reliability that formative assessment (SAT-0.81>FAT-0.52). When split-Half was used, summative assessment also had higher reliability that formative assessment (SAT-0.87>FAT-0.58). However, when test retest was applied, formative assessment had higher reliability than summative assessment (FAT-0.78>SAT-0.55). Based on this, it was recommended among others that teachers and test developers should rely more of summative assessment in the course of establishing the cognitive abilities of students.
Keywords: Assessment, Formative assessment, Reliability, Split-half, Test-retest., summative assessment. KR20