השוואת שיטות

	פונקציונליות פריט דיפרנציאלית אורכית (Longitudinal DIF)	ניתוח גורמים מאשר אורך
תחום	פסיכומטריה	פסיכומטריה
משפחה	Latent structure	Latent structure
שנת המקור	1980s–2000s	1970s–1990s
הוגה השיטה	Multiple contributors; foundational DIF methods by Lord (1980) extended to longitudinal designs	Karl Jöreskog (CFA framework); longitudinal extension by Wheaton, Muthén, and Alwin in the 1970s–1990s
סוג	Item-level bias detection across time	Longitudinal latent variable / measurement model
מקור מכונן	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.	Widaman, K. F. & Reise, S. P. (1997). Exploring the measurement invariance of psychological instruments: Applications in the substance use domain. In K. J. Bryant, M. Windle & S. G. West (Eds.), The science of prevention: Methodological advances from alcohol and substance abuse research (pp. 281–324). American Psychological Association.
כינויים	longitudinal DIF, DIF across time, temporal DIF, longitudinal item bias	longitudinal CFA, repeated-measures CFA, longitudinal measurement model, panel CFA
קשורות	6	6
תקציר	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.	Longitudinal confirmatory factor analysis (longitudinal CFA) applies a theoretically specified measurement model to data collected at two or more time points. Its primary purpose is to verify that a scale measures the same latent construct in the same way over time — a prerequisite for drawing valid conclusions about change from repeated-measures data.