Fig. 3
From: Investigating item complexity as a source of cross-national DIF in TIMSS math and science
ICCs When Fitting 2PL and LPE to the Studied Item, 8th Grade Math, TIMSS 2011. For Item M052206, the NCDIF index decreases from 1.447 to 0.110 when fitting 2PL versus LPE having \(\xi =15\), while the changes in RMSD are from 0.046 to 0.034 for the low proficiency country group, and from 0.041 to .021 for the high proficiency country group. For Item M032419, the NCDIF index reduces from 1.075 to 0.421 when fitting 2PL versus LPE having \(\xi =0.2\), while the changes in RMSD, are from 0.038 to 0.015 for the low proficiency country group, and from 0.048 to 0.021 for the high proficiency country group