مقایسهٔ روش‌ها

	متغیرهای ابزاری در پژوهش‌های آموزشی	روش تفاوت در تفاوت (Diff-in-Diff)
حوزه	استنتاج علّی	اقتصادسنجی
خانواده	Regression model	Regression model
سال پیدایش	1991 (canonical education application)	1994
پدیدآور	Angrist & Krueger (canonical 1991 education application); grounded in IV theory by Wright (1928)	Card & Krueger (canonical 1994 application); Angrist & Pischke (textbook treatment)
نوع	Quasi-experimental causal identification	Causal inference / panel regression
منبع بنیادین	Angrist, J. D., & Krueger, A. B. (1991). Does Compulsory School Attendance Affect Schooling and Earnings? Quarterly Journal of Economics, 106(4), 979-1014.	Angrist, J. D., & Pischke, J.-S. (2009). Mostly Harmless Econometrics: An Empiricist's Companion. Princeton University Press. ISBN: 978-0691120355
نام‌های دیگر	IV in education, 2SLS in education, education IV, school IV estimation	diff-in-diff, DiD, Farkların Farkı (Diff-in-Diff)
مرتبط	5	5
خلاصه	Instrumental variables (IV) estimation is a quasi-experimental strategy for isolating the causal effect of schooling or educational interventions when assignment to treatment is confounded by unobserved factors. Pioneered in education economics by Angrist and Krueger's use of quarter-of-birth as an instrument for compulsory schooling, IV finds a source of exogenous variation in exposure to education and uses only that variation to estimate outcomes such as earnings, test scores, or attainment.	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.