เปรียบเทียบวิธี

	การทดสอบยาหลอกในการวิจัยทางการศึกษา	Difference-in-Differences (DiD)
สาขาวิชา	การอนุมานเชิงสาเหตุ	เศรษฐมิติ
ตระกูล	Regression model	Regression model
ปีกำเนิด	1990s–2000s	1994
ผู้ริเริ่ม	Widely adopted in applied econometrics and education research; codified by Imbens, Wooldridge, Lee, and Lemieux	Card & Krueger (canonical 1994 application); Angrist & Pischke (textbook treatment)
ประเภท	Falsification / robustness check	Causal inference / panel regression
แหล่งต้นตำรับ	Imbens, G. W., & Wooldridge, J. M. (2009). Recent Developments in the Econometrics of Program Evaluation. Journal of Economic Literature, 47(1), 5-86.	Angrist, J. D., & Pischke, J.-S. (2009). Mostly Harmless Econometrics: An Empiricist's Companion. Princeton University Press. ISBN: 978-0691120355
ชื่อเรียกอื่น	placebo regression, falsification test, placebo check, fake-treatment test	diff-in-diff, DiD, Farkların Farkı (Diff-in-Diff)
ที่เกี่ยวข้อง	4	5
สรุป	A placebo test is a falsification check used in quasi-experimental education research to validate a causal design. By applying the same estimator to a time period, group, or outcome where no real effect should exist, researchers verify that their identification strategy is not picking up spurious patterns. A statistically significant placebo estimate signals a flaw in the design, while a null result supports its credibility.	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.