مقایسهٔ روش‌ها

	پژوهش توصیفی	طرح تحقیق پس از واقعه	طراحی پژوهش طولی
حوزه	طراحی پژوهش	طراحی پژوهش	طراحی پژوهش
خانواده	Process / pipeline	Process / pipeline	Process / pipeline
سال پیدایش	Late 19th century; formalized in social/behavioral sciences ~1960s–1980s	1960s (systematic codification); concept used in social science from early 20th century	Late 19th–early 20th century; methodologically codified through the 20th century
پدیدآور	Francis Galton, Karl Pearson (early empirical tradition); formalized in social science by Fred Kerlinger	Formalized by Fred N. Kerlinger; foundational treatment by Donald T. Campbell and Julian C. Stanley	No single originator; foundational methodological treatments by Stuart Menard and Judith Singer & John Willett
نوع	Non-experimental quantitative research design	Non-experimental quantitative research design	Quantitative (or mixed) observational research design
منبع بنیادین	Creswell, J. W. (2014). Research Design: Qualitative, Quantitative, and Mixed Methods Approaches (4th ed.). Sage. ISBN: 978-1452226101	Kerlinger, F. N. (1964). Foundations of Behavioral Research. Holt, Rinehart and Winston.	Menard, S. (2002). Longitudinal Research (2nd ed.). Sage Publications. ISBN: 978-0761922841
نام‌های دیگر	descriptive study, descriptive survey design, observational descriptive research, non-experimental descriptive research	after-the-fact research, retrospective non-experimental design, causal-comparative design, EPF design	longitudinal study, longitudinal design, prospective longitudinal study, repeated-measures observational study
مرتبط	3	3	4
خلاصه	Descriptive research is a non-experimental quantitative design that systematically documents the characteristics, frequencies, or distributions of variables in a defined population at a given point in time. It answers 'what is' questions — who, what, when, where, and how much — without manipulating variables or drawing causal conclusions. It is one of the most widely used research designs across the social, behavioral, health, and education sciences.	Ex post facto design is a non-experimental quantitative research approach in which the researcher investigates a phenomenon after it has already occurred, examining pre-existing differences between groups to explore potential causal or associative relationships. Because the independent variable cannot be manipulated — it happened in the past — the design relies on careful group selection, retrospective data collection, and statistical controls to approximate causal inference without experimental intervention.	Longitudinal research is an observational design in which the same participants, groups, or units are measured repeatedly over an extended period. Rather than capturing a single snapshot, it tracks change, stability, and temporal sequencing of variables — making it the primary non-experimental strategy for studying development, growth, decline, and the unfolding of causal processes across time.