The comparison of the ability of gifted and normal high school students based on classical test theory and item-response theory

The aim of this study was comparison the ability of gifted and normal high school students based on classical test theory and item-response theory. Two subsets of high school students, gifted (N=435, 220 boys and 215 girls), and normal students (N=449, 226 boys and 223 girls), ranging in age from 15 to 17, were tested by Cattell's Culture Fair Intelligence Test (CFIT) (Cattell, 1971), scale 3 (form A). The homogeneity reliability coefficients for gifted and normal students were 0.783 and 0.683 respectively, using Cronbach's alpha. Statistical testing showed that: 1) the mean of the gifted students on fluid intelligence was significantly higher than that of the normal students, 2) the correlation between raw scores and abilities for the gifted and normal students were 0.467 and 0.186 respectively, both of these coefficients and the difference of them were statistically significant, 3)comparison the abilities of the two groups based on IRT model showed that the abilities of gifted students on 80 th percentile and above are higher than that of normal students, the abilities of normal students on 20 th percentile and lower than this percentile are lower than that of gifted students, and the abilities of the two groups between the percentiles are are identical.