Assessing Local Dependence in Educational Performance ...

0' Alseasinlt ~ ~ . "7In.sen Table 1 about hereThe upper panel ~Table 2 provides the summa~" statistics for each cxamination.The data indicate that the reading examinations are slightly easy for an examinee of averageability and that the distributions of the raw scores are ncgatively skcwed. The meanpercentage of maximum scores are 51% for RD36, 60% for RDSI, and 64% for RD81.On the other hand, the mathematics examinations are quite difficult for an examinee ofaverage ability and the distributions of the raw scores are positively skewed. The meanpercentage of maximum scores are 39% for MC31, 34% for MC83, 22% for MFr31, and29% for MPSI.Insert Table 2 about hemProceduresSorting subjects into homogeneous score groups. The first step in the data analysisfor an examination was to use the raw score on the examination to sort subjects into fivehomogeneous score groups of approximately the same size.Descriptive statistics for the score groups are found in the lower panel of Table 2.It may be seen that among the five score groups constructed from each examination, thereis more variability in the group at the skewed tail of the score range. In order to make theinter-item correlations in each examination more compatible across score groups, the