I’m trying to figure out how to calculate black-to-white voter turnout at the county level. Can I aggregate the individual-level voter supplement extract data to the county level? Or is there a better way to calculate this county-level variable? I’ve seen it used in several studies, but I’m not sure of the best way to actually calculate and use it myself.
It is possible to calculate these turnout ratios using CPS data. However, CPS statistics are not very robust at the county level, especially with a single month of data. I’d recommend looking at studies and seeing the sources they use. This site has helpful guidance on how to estimate voting turnout rates. Some sources you may be interested in are official data from state governments such as this state data from Minnesota.
If you do decide to use CPS data, I would strongly recommend starting by reviewing the Voting and Registration Supplement sample notes so that you’re aware of the peculiarities of this sample. You will have to calculate these county-level ratios using the individual-level data that’s provided in the voter supplement. To find the total black and white population for each county you will want to sum VOSUPPWT for each value of RACE and COUNTY. To specifically find the population that is eligible to vote (i.e. persons age 18+ who are US citizens, including individuals who are native born, born abroad of American parents, or naturalized citizens), you will want to sum the weights only of those who are in the universe of VOTED (i.e. do not have a code of 99). You can then use VOTED again to sum the weights of everyone who answered that they voted by RACE and COUNTY. This will let you derive a voter turnout statistic by race which you can then use to create a black-to-white turnout ratio.
Also of note is that not all county codes are identified in the CPS. In fact, only about 45 percent of households in recent years are located in a county that is identified. This is important if in addition to calculating the voter turnout ratio you also want to know the names and locations of the counties in your sample.