来源:Barro : Economic growth in a cross section of countries.
Model1 - Model3, 因变量不同,但自变量相同。
growth = GDP0 + humancapital + governmentconsumption + policy (1)
invest = GDP0 + humancapital + governmentconsumption + policy (2)
fertility = GDP0 + humancapital + governmentconsumption + policy (3)
Model4 加入 invest 和fertility。
growth = GDP0 + humancapital + governmentconsumption + policy + invest + fertility (4)
问题:
为什么不对 model1-model3构造联力方程求解,而是估计model4?
谢谢。