This study examined longitudinal changes in Unified Tertiary Matriculation Examination (UTME) performance in selected South-Western states of Nigeria from 2010 to 2024. A retrospective longitudinal design was used to analyse annual aggregate data on candidate numbers, mean UTME scores, standard deviations, and the percentage of candidates scoring 200 and above. Descriptive statistics and ordinary least-squares linear regression were used to estimate temporal trends. In the reported series, the mean score increased from 187.45 in 2010 to 212.74 in 2024, while the proportion scoring 200 and above increased from 54.2% to 78.6%. A decline occurred in 2020, when the mean score fell to 198.23 and the proportion scoring 200 and above fell to 65.4%. The linear trend in mean score was positive and statistically significant (b = 1.58 points per year, R² = .904, p < .001), as was the trend in the percentage scoring 200 and above (b = 1.53 percentage points per year, R² = .905, p < .001). These results describe an upward trend in the supplied series but do not establish its causes. The findings underscore the importance of validating regional data against official state-level records before using them for planning. JAMB and education authorities should maintain comparable longitudinal records and strengthen the resilience of computer-based testing infrastructure, electricity supply, and connectivity.
Keywords: Educational Assessment, JAMB, South-Western Nigeria, UTME, examination performance, longitudinal analysis, trend analysis
