At least three different strata are recommended (for example, low, middle and high ability levels). In to show the relative distribution of item difficulty and students’ scores in a common metric, we constructed the variable map (Wright and Stone 1979). For equating between grades, we used a separate calibration design with anchoring items from one test when calibrating the other test (Wolfe 2004). After equating, we evaluated the quality of the link between the grade 1 and grade 3 tests by calculating the item-within-link statistic (Wright and Bell 1984). Under the null hypothesis of the items exhibiting perfect fit within the link, this statistic has an expected value of 1. Link adequacy was also evaluated by determining the stability of the item difficulty estimates across the grade 3 test with and without anchoring. To do that, we calculated the correlation between the item difficulty estimates. Appendix B. The results of the psychometric analysis for grades 1 and 3 physics The results for the physics tests are substantively similar to the mathematics tests and will be presented briefly because of space limitations. Five and six items were deleted from the grade 1 and grade 3 physics tests respectively because of poor psychometric quality. For further analysis we thus considered the sets of 40 and of 39 items for the grade 1 and grade 3 tests respectively. Of the 40 items for the grade 1 physics test, 17 demonstrated country-related DIF: 9 items in favour of China and 8 in favour of Russia. The other 23 items were DIF free and could be used
At least three different strata are recommended (for example, low, middle and high ability levels). In to show the relative distribution of item difficulty and students’ scores in a common metric, we constructed the variable map (Wright and Stone 1979). For equating between grades, we used a separate calibration design with anchoring items from one test when calibrating the other test (Wolfe 2004). After equating, we evaluated the quality of the link between the grade 1 and grade 3 tests by calculating the item-within-link statistic (Wright and Bell 1984). Under the null hypothesis of the items exhibiting perfect fit within the link, this statistic has an expected value of 1. Link adequacy was also evaluated by determining the stability of the item difficulty estimates across the grade 3 test with and without anchoring. To do that, we calculated the correlation between the item difficulty estimates. Appendix B. The results of the psychometric analysis for grades 1 and 3 physics The results for the physics tests are substantively similar to the mathematics tests and will be presented briefly because of space limitations. Five and six items were deleted from the grade 1 and grade 3 physics tests respectively because of poor psychometric quality. For further analysis we thus considered the sets of 40 and of 39 items for the grade 1 and grade 3 tests respectively. Of the 40 items for the grade 1 physics test, 17 demonstrated country-related DIF: 9 items in favour of China and 8 in favour of Russia. The other 23 items were DIF free and could be used
appendices_to_developing_instruments_to_assess_and_compare_the_quality_of_engineering_education-the_case_of_china_and_russia_0.docx