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	Projekt podłużny ex post facto	Badania panelowe
Dziedzina	Projektowanie badań	Projektowanie badań
Rodzina	Process / pipeline	Process / pipeline
Rok powstania	1964–1986 (Kerlinger 1964 first edition; Campbell & Stanley 1966)	1970s-1980s (econometric formalization); earlier social survey use from 1940s
Twórca	Fred N. Kerlinger (systematized); Donald T. Campbell & Julian C. Stanley (quasi-experimental framework)	Social science and econometric traditions; systematized by Cheng Hsiao and others from the 1970s-1980s
Typ	Non-experimental quantitative research design	Quantitative longitudinal observational design
Źródło pierwotne	Kerlinger, F. N. (1986). Foundations of Behavioral Research (3rd ed.). Holt, Rinehart and Winston. ISBN: 978-0030417498	Hsiao, C. (2003). Analysis of Panel Data (2nd ed.). Cambridge University Press. ISBN: 978-0521522717
Inne nazwy	longitudinal causal-comparative design, longitudinal after-the-fact design, longitudinal retrospective design, LEPF design	panel study, panel survey, longitudinal panel, repeated-measures panel
Pokrewne	5	3
Podsumowanie	A longitudinal ex post facto design combines the time-depth of longitudinal research with the retrospective logic of ex post facto inquiry. Participants are grouped by a naturally occurring characteristic or past event — not randomly assigned — and then observed or measured at multiple points over time. The goal is to trace how pre-existing differences between groups unfold or predict outcomes across an extended period, without the researcher ever manipulating the independent variable.	Panel research is a quantitative longitudinal design in which the same individuals, organizations, or other units are measured repeatedly across two or more time points. Unlike cross-sectional surveys that capture a single snapshot, a panel tracks change within units, enabling researchers to separate genuine within-unit change from between-unit differences and to model causal dynamics over time.