Janine Buchholz|Johannes Hartig
Comparing Attitudes Across Groups: An IRT-Based Item-Fit Statistic for the Analysis of Measurement Invariance
DIPF  Leibniz Institute for Research and Information in Education|DIPF  Leibniz Institute for Research and Information in Education
questionnaires assessment attitudes psychological traits crucial educational psychological research item response theory irt become viable tool scaling data many international largescale assessments aim comparing constructs across countries invariance measures across countries thus required recent cycle programme international student assessment pisa 2015 implemented innovative approach testing invariance irtscaled constructs context questionnaires administered students parents school principals teachers basis concurrent calibration equal item parameters across groups ie languages within countries groupspecific itemfit statistic root mean square deviance rmsd used measure invariance item parameters individual groups present simulation study examines statistics distribution different types extents noninvariance polytomous items responses five 4point likerttype items generated generalized partial credit model gpcm 1000 simulees 50 groups one five items either location discrimination parameters drawn normal distribution addition type noninvariance extent noninvariance varied manipulating variation distributions results indicate rmsd statistic better detecting noninvariance related betweengroup differences item location item discrimination studys findings may used starting point sensitivity analysis aiming define cutoff values determining noninvariance