手法を比較

	差分の差 (Difference-in-Differences, DiD)	フィールド実験	ランダム化比較試験 (RCT)
分野	計量経済学	実験計画法	実験計画法
系統	Regression model	Process / pipeline	Hypothesis test
提唱年	1994	1920s–1930s (agriculture); 1990s–2000s (social sciences)	1948
提唱者	Card & Krueger (canonical 1994 application); Angrist & Pischke (textbook treatment)	Formalized by R. A. Fisher (1935); systematized in social sciences by Harrison & List (2004)	James Lind (early precursor, 1747); modern formulation: Austin Bradford Hill & Medical Research Council (1948)
種類	Causal inference / panel regression	Experimental design	Interventional comparative study
原典	Angrist, J. D., & Pischke, J.-S. (2009). Mostly Harmless Econometrics: An Empiricist's Companion. Princeton University Press. ISBN: 978-0691120355	Harrison, G. W., & List, J. A. (2004). Field experiments. Journal of Economic Literature, 42(4), 1009–1055.	Schulz, K.F., Altman, D.G., Moher, D., for the CONSORT Group (2010). CONSORT 2010 Statement: Updated Guidelines for Reporting Parallel Group Randomised Trials. BMJ, 340, c332.
別名	diff-in-diff, DiD, Farkların Farkı (Diff-in-Diff)	field trial, natural field experiment, randomized field experiment, field RCT	RCT, randomised controlled trial, clinical trial, Randomize Kontrollü Çalışma (RCT) Tasarımı
関連	5	5	7
概要	Difference-in-Differences is a causal-inference method that estimates the effect of an intervention by comparing how a treatment group and a control group change over time. Made famous by Card and Krueger's 1994 minimum-wage study and developed in Angrist and Pischke's Mostly Harmless Econometrics, it isolates the treatment effect as the difference between the two groups' before-after changes.	A field experiment applies the logic of a randomized controlled trial in a naturally occurring, real-world environment rather than an artificial laboratory. Participants are randomly assigned to treatment and control conditions while going about everyday activities, allowing researchers to estimate causal effects with high internal validity while preserving a level of ecological realism that laboratory settings cannot offer. The design is especially prominent in economics, public health, political science, and development research.	A randomized controlled trial (RCT) is the gold standard experimental design in clinical and health research, in which participants are randomly allocated to a treatment group or a control group so that the effect of an intervention can be measured with the highest possible degree of internal validity. The modern parallel-group RCT was formalized by Austin Bradford Hill and the Medical Research Council in their landmark streptomycin trial of 1948, and its reporting is governed today by the CONSORT 2010 guidelines (Schulz et al., 2010).