"or" operator

[Beyza Emek]

Hi Statalist,

I would like to generate a group which includes female-asian students and female-european students.

a=1 for female
a=0 for male
b=1 for asian
b=2 for european
b=3 for african
b=4 for x
b=5 for y.......
b=6.....

gen G=1 if a==1 & b==1 | b==2

This command gives female students and all asian and all european students.
How should I correct my mistake?

Thank you
Beyza

[Clyde Schechter]

The order of Boolean operations in Stata, as in most programming languages, is that & takes precedence over |. So what you want is

gen G = 1 if a == 1 & (b == 1 | b == 2)

Comments: This generates a 1/. variable rather than a 1/0 variable. 1/0 variables are generally more useful. Also, while there is little difference when only two values of b are under consideration, with longer lists of alternatives, using the inlist() function is easier than enumerating a list of disjoined equalities. So, if I were doing this, it would be:

gen G = (a== 1 & inlist(b, 1, 2))

[Beyza Emek]

Great! Thanks a lot!