You could do a couple things here. It appears that there is almost no data missing from your "Population Estimates" file for Area_Name (count) and State, but it appears there are many "County" data points that are not reported in the NYT source.
One thing you could do is to use the "State" and "Area_Name" fields instead of the "County" and "State (Case Count NYT)" fields. The only caveat is that there will be a bunch of null values in your dataset. To try to combat this, you can create new measures and wrap them all in ZN(). This will say, if there is a null value, return a zero instead. Then you can try to proceed with that.
The other way that is probably better to go about this would be to blend your data, instead of trying to join the 2 sources together. Blend Your Data - Tableau
Hope this helps!
Thanks for the advice - unfortunately I'm still having issues. I'm getting error messages saying I can't use different levels of aggregation. I can easily create another workbook and do the analysis that way, but I would like to utilize the tool to it's fullest.
Do you know if it's possible to create 2 independent data connections within the same workbook? I could create a link at the county level and at the state level to arrive at the results I need. Basically create 2 tabs in each excel workbook and link the two for different analysis.
Thanks for the advice on ZN by the way - helpful for another task I'm trying to complete. Still learning tricks of the trade.
If you're using different levels of aggregation, you'd have to use data blending.
If you tried to join two data sources, one at city level, one at state level, you'd get a bunch of duplicates in your data and it would look funky (not the good kind).
For example, if you had data for Dallas and Houston from one source (cases) and data for Texas in another (population), your row-level data would look like this: