st: MIXLPRED: marginal effects after-MIXLOGIT-

[nagi kayo <kayonagi@hotmail.co.jp>]

Dear Professor Arne Risa Hole and all

 

I read the thread Professor Hole kindly wrote on "Mon, 6 Feb. 2012 13:18:34" about calculating marginal effects after -mixlogit- and tried to calculate marginal effects using the following commands.  in my estimation model, the number of alternatives is four, and "inc" is a demographic variable, and "price" is an alternative specific variable.

 

mixlogit d d1inc d2inc d3inc, group(id) rand(price)
mixlpred pred_base

replace d1inc=d1inc+1
replace d2inc=d2inc+1
replace d3inc=d3inc+1
replace d4inc=d4inc+1
mixlpred pred_inc


however, unexpectedly, "pred_inc" is quite similar to "pred_base," and thus the difference between the two is almost zero, which means that the marginal effect of income is almost zero. 

although i also tried the other explanatory variables, the results are not changed (in all cases, marginal effects are almost zero).

is my calculation of predicted probabilities wrong?

 

i greatly appreciate it if you would give me your advice.

 

with best wishes,

Kayo

  		 	   		  
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