<p>Y=B0+B1*X1+B2*X2+B3*X3+B4*X4+B5*X5+B6*X6+B7*X7+B8*X8+B9*X9+B10*X10+B11*X11+B12*X12+B13*X13+B14*Z+e1</p><p>There is a potential for endogeneity for Z.</p><p>Therefore Z=a0+a1*X14+a2*X15+a3*X16+e2</p><p>Z is endogeneity variable, X14,X15 and X16 are instrument variables.</p><p>方法一：</p><p>reg Z  X14  X15  X16</p><p>predict Zhat,（in order to get the predicted value of instrumenting equation)</p><p>predict u, res ( in order to get residual of instrumenting equation)</p><p>reg Y X1 X2 X3 X4 X5 X6 X7 X8 X9 X10 X11 X12 X13 Zhat u</p><p>test u</p>