Missing Data in University Entrance Exams: Theoretical Bases and Evidence Based on Real Data

Document Type : Original Article




Missing data that refer to any non-answering to items is a common phenomenon of empirical studies, educational and psychological assessments. Different statistical methods for dealing with nonresponse data are affected by the mechanism of missing-ness, their causes and their extent. The purpose of this article is exploring and describing the missing data in the university entrance national exam. Data for General Persian Literature Test of mathematical, Empirical and humanity Science fields and professional tests including literature in humanity filed, biology in empirical field and mathematics in math field in 1383, 1391 and 1395 (Solar years) used for this purpose. Analysis was done by SPSS, R and ‘psych’ package in R. It is shown the amount of missing data has increased in the years under review (min 2.2% and max 91.6%). Under amusingness condition item difficulties are overestimated. It is also shown that there is a high positive correlation between the number of non-answered items in different test of the same year (rmin = 0.41 and rmax=0.78); and the high negative correlation between the number of correct responses and missing answers (rmin = -0.56 and rmax =-0.85). The results of show occurrence of missing data in various competence dimensions and non-ignorable of missing data in statistical analyzes. It is necessary to select and use appropriate method for missing data when analyzing data for university entrance national exam.





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