השוואת שיטות

	מדידת השתנות פוליטומית	תפקוד פריט דיפרנציאלי (DIF)
תחום	פסיכומטריה	פסיכומטריה
משפחה	Latent structure	Latent structure
שנת המקור	2000–2004	1970s–1993
הוגה השיטה	Roger E. Millsap, Robert J. Vandenberg	William H. Angoff and colleagues (ETS); systematized by Holland & Wainer
סוג	Multi-group confirmatory test	Item-level bias detection
מקור מכונן	Millsap, R. E. & Kwok, O.-M. (2004). Evaluating the impact of partial factor loading and intercept invariance on selection utility. Psychological Methods, 9(2), 200–215.	Holland, P. W. & Wainer, H. (Eds.) (1993). Differential Item Functioning. Lawrence Erlbaum Associates. ISBN: 978-0805809589
כינויים	PMI, ordinal measurement invariance, polytomous factorial invariance, polytomous multi-group measurement invariance	DIF, item bias analysis, measurement non-equivalence, item-level measurement bias
קשורות	5	5
תקציר	Polytomous measurement invariance testing evaluates whether a scale with ordered categorical (polytomous) response options — such as Likert-type items — measures the same latent construct in the same way across two or more groups. It extends classical multi-group CFA invariance testing to properly account for the ordinal nature of item responses, ensuring that group comparisons of latent means or factor structures are substantively valid.	Differential item functioning identifies test or survey items that behave differently for examinees from different groups — such as gender, ethnicity, or language background — after controlling for the underlying ability or trait being measured. DIF analysis is essential for fairness evaluation in educational testing and psychological scale development.