השוואת שיטות

	הפרש-בהפרשים (דיד)	ניסוי מבוקר אקראי (RCT)
תחום	אקונומטריקה	תכנון ניסויים
משפחה	Regression model	Hypothesis test
שנת המקור	1994	1948
הוגה השיטה	Card & Krueger (canonical 1994 application); Angrist & Pischke (textbook treatment)	James Lind (early precursor, 1747); modern formulation: Austin Bradford Hill & Medical Research Council (1948)
סוג	Causal inference / panel regression	Interventional comparative study
מקור מכונן	Angrist, J. D., & Pischke, J.-S. (2009). Mostly Harmless Econometrics: An Empiricist's Companion. Princeton University Press. ISBN: 978-0691120355	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.
כינויים	diff-in-diff, DiD, Farkların Farkı (Diff-in-Diff)	RCT, randomised controlled trial, clinical trial, Randomize Kontrollü Çalışma (RCT) Tasarımı
קשורות	5	7
תקציר	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 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).