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	Longitudinell forskning	Relationsundersökning
Ämnesområde	Forskningsdesign	Forskningsdesign
Familj	Process / pipeline	Process / pipeline
Ursprungsår	Late 19th–early 20th century; methodologically codified through the 20th century	Mid-20th century onward (systematised ~1960s–1990s)
Upphovsperson	No single originator; foundational methodological treatments by Stuart Menard and Judith Singer & John Willett	Established in educational and social science research methodology; systematised by Fraenkel & Wallen and others
Typ	Quantitative (or mixed) observational research design	Quantitative non-experimental survey design
Ursprungskälla	Menard, S. (2002). Longitudinal Research (2nd ed.). Sage Publications. ISBN: 978-0761922841	Fraenkel, J. R., Wallen, N. E., & Hyun, H. H. (2009). How to Design and Evaluate Research in Education (8th ed.). McGraw-Hill. ISBN: 978-0073525748
Alias	longitudinal study, longitudinal design, prospective longitudinal study, repeated-measures observational study	correlational survey, associational survey, relationship survey design, relational descriptive survey
Närliggande	4	4
Sammanfattning	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.	Relational survey research is a quantitative, non-experimental design that gathers structured self-report data from a sample and examines the statistical associations among two or more variables. Unlike purely descriptive surveys, which only characterise distributions, relational surveys ask whether and how strongly variables co-vary — providing evidence of relationships without manipulating conditions or establishing causation.