Z-Score Demystified: a Critical Analysis of the Sri Lankan University Admission Policy

Document Type



Published in: Journal of Case Studies in Education, February, 2011


In the year 2001, the University Grants Commission of Sri Lanka successfully appealed to change the method of determining the cut-off scores for university admissions from raw scores to standardized z-scores. This standardization allegedly eliminated the discrepancy caused due to the assumption of equal difficulty levels across all subjects. This paper analyzes the effectiveness of using z-score cut-offs for university admissions compared to raw score cut-offs. For the purpose of the analysis, only those students who were admitted to Sri Lankan universities on the basis of the district quota were considered. The Wilcoxon Rank Sum test was used for this analysis. The samples that were taken are independent and no assumptions were made on the probability distributions other than the fact that they are continuous.