Dear All
I found that gretl provides a nice "slope" feature in Probit and Logit models.
However, when independent variables are discrete, gretl computes
slopes as they are continuous variables. I compare gretl's result with
other packages, such as STATA and Matlab (the Probit output produced
by Matlab are attached below)
They will automatically detect the discrete variables in Probit (as
well as in Logit) to compute the slope (also named as marginal
effects) and mark them in a footnote:
"(*) dy/dx is for discrete change of dummy variable from 0 to 1."
Do you think our gretl should do the same thing?
Thanks
Yi-Nung
===MATLAB output ===
Probit Regression
Regressor Coefficient Std. Error t-stat Prob>|t|
------------------------------------------------------------------
constant -2.81108 0.65883 -4.26678 0.00002
variable1 0.00159 0.00064 2.47531 0.01373
variable2* 0.27799 0.18129 1.53338 0.12599
variable3 0.36204 0.19664 1.84112 0.06636
variable4 0.00041 0.00024 1.70164 0.08961
variable5* -0.12469 0.13433 -0.92821 0.35387
variable6* -0.07526 0.13467 -0.55887 0.57657
------------------------------------------------------------------
(*) indicates that the variable is a dummy
Marginal Effect
Regressor Marginal Std. Error t-stat Prob>|t|
------------------------------------------------------------------
variable1 0.00056 0.00023 2.48203 0.01348
variable2* 0.10175 0.06855 1.48438 0.13851
variable3 0.12732 0.06907 1.84341 0.06602
variable4 0.00014 0.00008 1.70222 0.08951
variable5* -0.04386 0.04722 -0.92888 0.35352
variable6* -0.02648 0.04739 -0.55876 0.57665
------------------------------------------------------------------
(*) dy/dx is for discrete change of dummy variable from 0 to 1.