 መሣሪያ ተለዋዋጮች መግቢያ ለማግኘት ተመልከት Angrist and Pischke (2009) (ያነሰ መደበኛ) ወይም Angrist, Imbens, and Rubin (1996) (በተጨማሪ መደበኛ).
Pakuti chiyambi zosintha zoimbidwa kuona Angrist and Pischke (2009) (zochepa ofunda) kapena Angrist, Imbens, and Rubin (1996) (more ofunda).