截一张Hanson(1999)的图,对比xtthres的定义。
语法格式:xtthres varlist [if] [in] , thres(varname) dthres(varname) [ qn(#) bs1(#) bs2(#) bs3(#) levle(#) minobs(#) ]
解释:
1、thres(varname) specifies threshold variable, as denoted by q_it in Hansen(1999). Note that this option should not be omitted.
2、dthres(varname) specifies the variable that will show threshold effects, as denoted by x_it in Hansen(1999). This variable will be multipled by the indicator function I(.). Note that this option should not be omitted either.
3、 qn(#) specifies the number of distinct values to be search in finding out the optimal estimate of threshold effects, r_hat, which will minimize the sum of square residuals of the model. The default value is 400.
例子:
xtthres tobin size tang prof, th(grow) d(tl)
可以看出,dthres(varname) 对应的是x_it
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