Referencing a numerical variable with a multi-letter value fode

[Nick Wolfinger]

I'm working with the NORC release version of the General Social Survey, and the REALINC variable. This is a quantitative variable, storage type double. Missing cases are coded "iap," as opposed to more common missing value designators like ., .a, .i, etc.

How do I reference these values in a STATA command? I've never seen missing data with a three letter value before. Thanks.

[Nick Cox]

My guess is that iap is a value label, as otherwise such a value can’t be stored in a double.

[Nick Wolfinger]

Thank you. That indeed turned out to be the case. I'd never seen anyone apply a value label to a missing data code, so I hadn't considered that.

[Clyde Schechter]

It's not that uncommon to see missing values with value labels. Most often it is done where there are several categories of missing values and there is some need to distinguish them. So one might have separate missing values and labels for "Refused to Answer," "Didn't Know," "Not Applicable," "Multiple Responses Apply," etc.