Hi Statalist,

I am doing a simple probit model in which the dependent variable is "work" (1 if the person is employed and 0 if the person is unemployed) and among the independent variables I have an interaction between the birth cohort and the age of each individual.

Since one of the main elements of my research is the difference of the three age groups within each cohort, I would like to show the estimated employment for the first cohort on each age group and then show the marginal effects of succesive cohort. For this, I am trying to use the Clarify package, with the marginal effects simulated at the mean age of the corresponding age group, setting all other covariates at their sample mean.

The thing is I am having trouble with the interaction between the age group and cohort (not when I do the probit, but when I do the probit in the clarify package).

This is an example dataset that I have created to ilustrate the data I am currently using:

Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input float(id work cohort age age_group sex educ age_40 age_50 age_64)
 1 1 1 43 1 1 1  3  0 0
 2 0 2 56 2 2 3 16  6 0
 3 0 3 64 3 2 3 24 14 4
 4 1 1 58 2 1 2 18  8 0
 5 0 2 63 3 1 1 23 13 3
 6 1 2 49 1 1 4  9  0 0
 7 0 1 52 2 2 2 12  2 0
 8 1 3 44 1 2 4  4  0 0
 9 1 2 62 3 2 1 22 12 2
10 0 3 43 1 1 4  3  0 0
end
label values work work
label def work 0 "Unemployed", modify
label def work 1 "Employed", modify
label values cohort cohort
label def cohort 1 "1901-1910", modify
label def cohort 2 "1911-1920", modify
label def cohort 3 "1921-1930", modify
label values age_group age_group2
label def age_group2 1 "40-49", modify
label def age_group2 2 "50-59", modify
label def age_group2 3 "60-64", modify
label values sex sex
label def sex 1 "Men", modify
label def sex 2 "Women", modify
label values educ educ
label def educ 1 "MS", modify
label def educ 2 "HS", modify
label def educ 3 "UG", modify
label def educ 4 "GS", modify
When I run the:
Code:
estsimp probit work i.age_group#i.cohort sex educ age_40 age_50 age_64
I get the message: "factor variables not allowed r(101)"

(age_40 is the age minus 40; age_50 is the age minus 50 (0 if negative); and age_60 is the age minus 60 (0 if negative)).

I guess one solution is to run the probit for each age group, but when I do it, I get the following message and lose two of the coefficients:
"Stata has dropped one of your independent variables.
Please re-specify your model and try again."

Do you have an idea of how could I solve this?

Thanks in advance,
Isidora.