Strong True Test Score Theory Analysis of Item Location and Slope Indices of Oyo State Junior Secondary School Certificate Mathematics Test Items

This study has been undertaken to investigate item location
(difficulty) and slope (discrimination) indices of Oyo State Junior Secondary
School Certificate Examination (JSSCE) mathematics multiple-choice test
items using the strong true test score theory (STTST) method. The study adopted
a descriptive survey design. A sample of 600 candidates was selected using
multi-stage sampling techniques from a population of 95,419 students who sat
for the 2016 JSSCE Mathematics Paper 1 in Oyo State, Nigeria. An adoption
version of the 2016 Oyo State JSSCE Mathematics Paper 1 titled “Mathematics
Test” (MT) instrument was adopted for information aggregation. Data collected
were analysed using BILOG-MG 3.0 software bundle. The solutions for item
location under the 1, 2, and 3PL models found easy items to be 50, 42 and 25,
ideal items stood at 8, 13 and 23, while difficult items stood at 2, 4 and 9 items
respectively. Results for item slope under the 2PL and 3PL models found items
with high slopes to be 2 and 18, moderate slopes stood at 23 and 29, while poorly
sloped items stood at 34 and 10 respectively. Lastly, the results for pseudoguessing under the 3PLM found 30 items to have a high degree of probability.
In closing, the Oyo State 2016 JSSC Mathematics Examination under the strong
true test score theory analysis had a moderate psychometric quality. It showed
that most examinees including low ability examinees, had at least a moderate
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probability of answering the items along the MT correctly considering the individual examinee item location on the test, which signified that, the MT could
not discriminate between examinees that understood the open content and those
who do not.