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	Długoterminowe różnicowanie pozycji testowej (Longitudinal DIF)	Testowanie niezmienniczości pomiaru
Dziedzina	Psychometria	Psychometria
Rodzina	Latent structure	Latent structure
Rok powstania	1980s–2000s	2000
Twórca	Multiple contributors; foundational DIF methods by Lord (1980) extended to longitudinal designs	Vandenberg & Lance
Typ	Item-level bias detection across time	Multi-group confirmatory factor analysis procedure
Źródło pierwotne	Millsap, R. E., & Kwok, O. M. (2004). Evaluating the impact of partial factorial measurement invariance on selection in two groups. Psychological Methods, 9(1), 93–115.	Vandenberg, R. J., & Lance, C. E. (2000). A review and synthesis of the measurement invariance literature. Organizational Research Methods, 3(1), 4–70.
Inne nazwy	longitudinal DIF, DIF across time, temporal DIF, longitudinal item bias	Factorial Invariance, Measurement Equivalence, Configural-Metric-Scalar Testing, Ölçüm Değişmezliği
Pokrewne	6	3
Podsumowanie	Longitudinal differential item functioning detects whether individual test or scale items behave differently across measurement occasions for the same respondents. It extends standard DIF methodology to repeated-measures designs, ensuring that observed change scores genuinely reflect construct change rather than shifts in item characteristics over time.	Measurement invariance testing is a sequence of nested confirmatory factor analysis (CFA) models that examines whether a psychological scale measures the same latent construct in the same way across distinct groups or time points. Systematized and popularized by Vandenberg and Lance (2000), the procedure tests a hierarchy of constraints — from identical factor patterns to identical item intercepts — so that researchers can justify meaningful group comparisons on latent means.