门槛分析,结果显示option / not allowed是什么情况，新手练习，请大家多多指点
. xthreg i q1 q2 q3 d1 qd1, rx(c1) qx(d1) thnum(1) grid(400) ///  trim(0.01) bs(300)
Estimating  the  threshold  parameters:   1st ......  Done
Boostrap for single threshold
.................................................. +   50
.................................................. +  100
.................................................. +  150
.................................................. +  200
.................................................. +  250
.................................................. +  300

Threshold estimator (level = 95):
-----------------------------------------------------
     model |    Threshold         Lower         Upper
-----------+-----------------------------------------
      Th-1 |       0.0154        0.0141        0.0167
-----------------------------------------------------

Threshold effect test (bootstrap = 300):
-------------------------------------------------------------------------------
Threshold |       RSS        MSE      Fstat    Prob   Crit10    Crit5    Crit1
-----------+-------------------------------------------------------------------
    Single |   17.7818     0.0023      35.20  0.0000  13.0324  17.4336  24.0428
-------------------------------------------------------------------------------
option / not allowed
r(198);