Development and Calibration of Geometry Diagnostic Test for Upper Basic Education Students in Plateau State, Nigeria

This paper developed and calibrated a geometry diagnostic test for Upper Basic Education students in Plateau State, Nigeria. The purpose of the paper was to improve the performance of students in mathematics through the mastery of geometry contents which many Nigerian students found difficult. The study utilized instrumentation and survey research designs. The population was 20,550 UBE 3 students from Plateau Central Senatorial Zone drawn using probability proportionate to size sampling method. The validity of the UBE 3-GDT was estimated through experts’ judgment, test blue prints and data model fit while reliability was estimated using test information function. The study was guided by four research questions. Data analyses were by chi- square goodness of fit statistics and item analysis indices. The finding of the study revealed that the diagnostic items fit the 3PLM. The test information function 3.278 obtained through the use of the maximum likelihood estimate statistics indicated a high reliability of between 0.75 and 0.91. In terms of difficulty, 93% of items had indices between 0 and 0.5, indicating that they were acceptable for diagnostic tests. The discrimination indices range from fair to moderate, that is, 0.20 to 0.50 and 0.50 to 1.00, and pseudo-guessing of 96% of items was within the acceptable range, that is, 0.20