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	Longitudinell forskning	Undersökningsforskning
Ämnesområde	Forskningsdesign	Forskningsdesign
Familj	Process / pipeline	Process / pipeline
Ursprungsår	Late 19th–early 20th century; methodologically codified through the 20th century	Late 19th century; methodologically systematised 1940s–1960s
Upphovsperson	No single originator; foundational methodological treatments by Stuart Menard and Judith Singer & John Willett	Francis Galton, Charles Booth, and early social statisticians; systematised by Paul Lazarsfeld and colleagues at Columbia in the 1940s
Typ	Quantitative (or mixed) observational research design	Quantitative (and mixed) non-experimental design
Ursprungskälla	Menard, S. (2002). Longitudinal Research (2nd ed.). Sage Publications. ISBN: 978-0761922841	Fowler, F. J. (2014). Survey Research Methods (5th ed.). Sage Publications. ISBN: 978-1452259000
Alias	longitudinal study, longitudinal design, prospective longitudinal study, repeated-measures observational study	survey methodology, questionnaire research, survey design, survey study
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.	Survey research is a quantitative (and sometimes mixed-methods) design in which a researcher collects standardised self-report data from a sample drawn from a defined population, using a questionnaire or structured interview. It is the dominant non-experimental strategy for describing population characteristics, estimating prevalence, mapping attitude distributions, and testing bivariate or multivariate associations across social, behavioural, and health sciences.