Changing yes/no observations into 1/0

[Nick Baradar]

I have a list of variables that contain answers Yes and No, I am trying to replace them with 1 and 0 and make all of them numeric
The command that I use is the following:

foreach var in MY LIST OF VARIABLES {
replace `var' = 0 if `var'==`No'
replace `var' = 1 if `var'==`Yes'
destring `var', replace
}


Stata responds "no variables defined". I would appreciate your help on this.
Thank you in advance!

[Joseph Coveney]

Maybe try

foreach var of varlist <MY LIST OF VARIABLES> {
    replace `var' = strtrim(strproper(`var'))
    replace `var' = "0" if `var' == "No"
    replace `var' = "1" if `var' == "Yes"
    replace `var' = ".m" if !inlist(`var', "No", "Yes")
}
destring <MY LIST OF VARIABLES>, replace

[Nick Baradar]

Dear Joseph Coveney , thank you very much for your reply.
My observations after the commands you wrote above turned ".m". And I tried the same commands but without the line "replace `var' = ".m" if !inlist(`var', "No", "Yes")", and it did work - I got observations with 0s and 1s. Can you please explain what's the meaning of that line and what if I escaped it. Thank you in advance!

[Joseph Coveney]

Yeah, sorry, that ought to have been first, before converting Noes and Yeses to zeros and ones.

foreach var of varlist <MY LIST OF VARIABLES> {
    replace `var' = strtrim(strproper(`var'))
    replace `var' = ".m" if !inlist(`var', "No", "Yes") // or: assert inlist(`var', "No", "Yes")
    replace `var' = "0" if `var' == "No"
    replace `var' = "1" if `var' == "Yes"
}
destring <MY LIST OF VARIABLES>, replace