Nature计算科学综述：经由准实验，从观察数据中推测因果关系(18)

40. NCI funding policy for RPG awards. NIH: National Cancer Institute https://deainfo.nci.nih.gov/grantspolicies/fnalfundltr.htm (2020).
41. NIAID paylines. NIH: National Institute of Allergy and Infectious Diseases http://www.niaid.nih.gov/grants-contracts/niaid-paylines (2020).
42. Keele, L. J. & Titiunik, R. Geographic boundaries as regression discontinuities. Polit. Anal. 23, 127–155 (2015).
43. Card, D. & Krueger, A. B. Minimum Wages and Employment: A Case Study of the Fast Food Industry in New Jersey and Pennsylvania Working Paper No. 4509 (NBER, 1993); https://doi.org/10.3386/w4509
44. Ashenfelter, O. & Card, D. Using the Longitudinal Structure of Earnings to Estimate the Efect of Training Programs Working Paper No. 1489 (NBER, 1984); https://doi.org/10.3386/w1489
45. Angrist, J. D. & Krueger, A. B. in Handbook of Labor Economics Vol. 3 (eds. Ashenfelter, O. C. & Card, D.) 1277–1366 (Elsevier, 1999).
46. Athey, S. & Imbens, G. W. Identifcation and inference in nonlinear diference-in-diferences models. Econometrica 74, 431–497 (2006).