黃河泉 发表于 2017-4-10 16:26
没错,或许你也想试试 (ssc install utest),可以正式检定是否存在 U or inverted-U shape。
黄老师您好,我按照您的代码做出来是这个结果,我查了很多资料都没有找到这个的解释,老师您能否和我解释一下,感激
Specification: f(x)=x^2
Extreme point: .0188902
Test:
H1: U shape
vs. H0: Monotone or Inverse U shape
-------------------------------------------------
| Lower bound Upper bound
-----------------+-------------------------------
Interval | -156.6146 519.1631
Slope | -13.54852 44.90505
t-value | -1.0813 1.081918
P>|t| | .1397904 .1396531
-------------------------------------------------
Overall test of presence of a U shape:
t-value = 1.08
P>|t| = .14
.
end of do-file