... xx=nxtxtx2t17. CAUSALITY AND INFERENCE 475A third variable indicates who receives the treatment. I.e, he has the “causal in- dicator” s which can take two values, t (treatment) and c (control), and two ... variablesyt and y c , which, evaluated at individual ω, indicate the responses this individualwould give in case he was subject to the treatment, and in case he was or not.Rubin defines yt− y c to ... into the model.Alternatives minimize Amemiya’s prediction criterion or Akaike’s informationcriterion, which minimize functions of the estimated variances and n and k. Akaike’sinformation criterion...