核心观点/结论

政策对经济的影响是值得怀疑的（长期，作者使用5年平均的数据考察）。

作者的政策是宏观经济和贸易政策。

政策变量的极值对经济的影响是显著的。

The outlyingobservations of inflation, budget deficits, and black market premium arerealizations of extreme ‘bad policies”. The outlying observations of trade/GDPand M2/GDP are realizations of extreme “good policies”. It is econometriccommonsense that extreme observations can be very influential in determiningstatistical significance of right-hand side variables.

非极值又是什么情况？

How do theabove regressions do over more moderate ranges of policy variables?

All six policyvariables become insignificant, and the F-statistic for their joint effect alsofalls short of significance.

解释

It is a lot easier to cut down a tree than to grow one.

Countries that pursue destructive policies are plausible candidates to miss out on growth. However, it doesn’t follow that one can create growth with relative macroeconomic stability. The policies are inherently asymmetric.

另一种解释

门槛突变，达不到一定程度不会有效果。

IV问题

Mankiw (1995)noted sarcastically, if I instrument for the price of apples with the laggedprice of apples in an equation for the quantity of apples, is it the supply ordemand equation that I have identified?