egen rowtotal if not missing

[Al Bothwell]

I want to get a row total of nine variables if none is missing. Is my code correct?

egen phq_total=rowtotal(phq1 - phq9) if !missing(phq1 | phq2 | phq3 | phq4 | phq5 | phq6 | phq7 | phq8 | phq9)

[Nick Cox]

No. It's not correct. Consider just phq1 | phq2 which will be returned as 1 or true is either variable is missing (because missing is not zero) and as 0 or false if neither is missing. By an extension of the same argument what you feed to !missing() will be either 1 or 0 and it can never be missing. If you change the pipes to commas, I think you are where you want to be.

However, I'd go

egen phq_miss = rowmiss(phq?)

egen phq_total = rowtotal(phq?) if phq_miss == 0

as I would trade off creating a new variable against less typing and a less error-prone code.


All that said

gen wanted = phq1 + phq2 + phq3 + phq4 + phq5 + phq6 + phq7 + phq8 + phq9

will be missing if any of the variables on the right is missing, which is what you are asking for.

[Al Bothwell]

Thanks, Nick. I used the simple option:

 
 gen wanted = phq1 + phq2 + phq3 + phq4 + phq5 + phq6 + phq7 + phq8 + phq9