In some of the new 2018 data releases, there is a variable containing square miles that can be used to calculate the area of a geography. You can also use in conjunction with a population variable to calculate the population density.
Some caution should be used when running a report with either of these variables due to the nature of the reports and the formatting of the numbers. The recommended method would be to use the Data Export tool in ENVISION instead. This example will show both a report and an export so you can see the difference.
The first step is to create a custom variable for population density. You will need to create a Ratio variable, choosing Population divided by the Area. I used Pop-Facts Premier 2018 and it looks like this:
Don't forget to save the changes!
You can find more detailed information about creating custom variables here: https://community.environicsanalytics.com/hc/en-us/articles/115001860772-ENVISION5-QuickStart-US-Creating-and-Editing-Custom-and-Favorite-Variables
Once you have that created, and some geographies created, you can run the Data Export tool.
Select either Standard Geography or My Areas, depending on the geographies you wish to analyze. (Standard Geography allows you to pick a smaller level of geography within an existing one, whereas My Areas allows you to pick several existing ones. This example will illustrate My Areas.)
Select a geography as a Universe or Benchmark by clicking the checkmark.
Select the areas you wish to analyze.
Select your created variable (and any others you wish).
You can navigate to the Results page to see the output.
When you click on it, it will open/download a CSV file.
If you had run a Ranking Variables - Trade Area report (for Troy, NY), the output would look like this:
The numbers are still there, but because of the way our report is formatted, they can be confusing. The population density appears in the % column, because it was originally built as a Ratio custom variable. And the Land Area appears in the Count column, but does not get any decimal places.
As you can see, it's much easier to use the Data Export tool in a situation like this.