Hello, I'm analyzing some data and need to test whether a 2SLS or OLS model is most appropriate. I understand that I need to run the Hausman specification test and the syntax provided in the SAS documentation looks straightforward but I'm not sure how to execute the code. The data contain a dependent variable Y, a mediator M, and two instruments X and Z, and their interaction. the model I'm testing is Y = M + X + Z + X*Z. The code provided in the SAS help guide under 'Hausman specification test' is provided below. My question is what needs to be inputted. What do y1 and y2 represent below? Does p represent predicted values? I assume interc refers to an interaction term? And what is d2? proc model data=one out=fiml2; endogenous y1 y2; y1 = py2 * y2 + px1 * x1 + interc; y2 = py1* y1 + pz1 * z1 + d2; fit y1 y2 / ols 2sls hausman; instruments x1 z1; run; Any help and even an example would be much appreciated. Thanks! ... View more