Dear Statalist,
I hope you are well. Please, I would like to ask regarding the Heckman selection model, how to apply it with my categorical data. In fact, I have four categories in one column referred to as dependent variables. At first, I have analyzed the estimation of these variables using Multinomial logit regression. However, in order to test the selection bias, have been advised to apply Heckman probit selection model using Stata.
My question is how to apply the hackman model over the four dependent variables? Do I need first to create a sperate table of dataset for each dependent variable? Or can I keep them in one column and the software is intelligent to select the required dependent variable for each stage? Regarding the Stata command, should I use the syntax command for each stage with only changing the dependent variable?


The command: heckman depvar [indepvars], select(depvars = varlists) [twostep]
I have 300 firms as sample size; dealing with 32 independent variables. Each firm has to choose one decision of the four categories (i.e. dependent variables). The below Table shows my idea to employ the analysis of hackman over the dependent variables in three stages.
Could you please advise me on how to apply the Heckman model for the 3 stages?
Stage 1 analyzing all firms (300 n) Stage 2 Analyzing Firm B Stage 3 Analysing Firm C
dependent variable Firm decide A (87n)
dependent variable Firm decide C (103 n)
dependent variable Firm decide E (83n)
dependent variable Firm decide B(213 n)
dependent variable Firm decide D (110 n)
dependent variable Firm decide F (20n)
Note: the letters from A to F is the type of firms’ decision and is considered to be the dependent variable. (n) refer to the number of firms in each category of the dependent variable
Your kind help and support greatly appreciated
Kind regards,
Rabab