Background; Data Sources
To determine the average sales price, I pulled data from the City of Milwaukee’s OpenData site. This file contained the square footage, property type, and even lot sizes of various properties sold in 2018 (among other things). What became a pain was structuring my data so that I could compare it against the Census’ income data.
The sales data included addresses but not census tract information. Luckily, the Census has a batch geocoding tool so I didn’t have to painstakingly geocode 5,000+ sales entries separately. Perhaps, I’m getting a bit ahead of myself… “geocoding”?
Per the Census’ own technical documentation, geocoding is “an address look-up tool that converts your address to an approximate coordinate (longitude/latitude) and returns information about the address and the census geography.” If you geocode on the Census website, you’ll get a result such as this below.
Pretty boring and a bit noisy. The relevant data point here is “Census Tract 77”. A more interesting view can be found at the FFIEC’s (Federal Financial Institution Examination Council) website. Here, you can enter an address and see demographic data, and a map view of the census tract you’re looking for. Fun!
The specific Census report I used was “DP03: Economic Characteristics” with the geographic constraints of all Census tracts in Milwaukee County, Wisconsin. Now onto the analysis!
What I Learned
The trend line that resulted in Tableau was:
- Avg. sales price of homes in a Census Tract = 2.02485 * Average Family Income of the Census Tract
- R2 = 0.928
- P-value: <.001
So it seems we’ve got a fairly significant relationship between the two variables – neat!
Overall, the results didn’t surprise me. The five outlying data points are all census tracts in Milwaukee’s “East Side” and there are quite a few properties within those tracts that offer views of Lake Michigan. The point at the top of the graph, Census Tract 143, contains high rises where a few Bucks and Brewers players are rumored to reside.
This was a fun first exercise. I’m looking forward to much more analysis and knowledge sharing in the future. Thanks for reading!!
P.S. – My public tableau can be found here.