Creating unique IDs for PUMAs


I’m using PUMAs as my geographic unit of analysis for a project using the ACS2012 5 year file. I know that the PUMA codes are state dependent, so I’ve created a unique puma id by combining them with the statefips variable, using the following r code:

fam$pumaid = paste(as.numeric(fam$statefip), as.numeric(as.character(fam$puma)), sep="-").

This gives me an ID code with the following format: “[statefip code] - [puma code]”. My problem is that this returns 3344 unique IDs, whereas there are only 2378 PUMAs. Any idea what I’m doing wrong?

Thanks so much for your help!



In the 2012 ACS 5-year file, the PUMA variable for respondents from 2008-2011 is coded based on the 2000 Census boundaries, while PUMA is coded based on the 2010 Census boundaries for 2012 respondents. As a result, the total number of PUMAs in the file will be greater than the number of PUMAs in any one of the coding schemes alone.

Hope this helps.