Do you deer hunt in Wisconsin? Have you had your deer tested for chronic wasting disease? I recently learned the results of the test on my deer and was curious about the results statewide.
Bringing in the data
The county data are available online at dnr.wi.gov. I used SelectorGadget to identify the columns of data I wanted from each page and the rvest package of R to do the extraction, looping through the pages with different years of data. You can see the code that I used here.
In preparation for mapping the results, I also downloaded state and county mapping data for Wisconsin from the ggplot2 package.
Summarizing the data
Then I summarized the test data, determining the first year that CWD was detected in each county and the percentage of positive results over all tests during 1999-2019 and just during 2019.
Since 1999, 28 of 72 Wisconsin counties have tested positive for CWD, including 2 counties that tested positive for the first time in 2019: Sheboygan, Dunn.
Mapping the data
I used the data to create a county map showing the percentage of positive results in 2019, the counties that have never tested positive for CWD, and the first year of detection.
Then I created a whole series of maps, one for each year of testing, to see how the counties with positive detections have expanded over time.
Plotting the data
Finally, to see the progression of the infection in the deer population over time, I plotted the percentage of positive results for every county that ever had a positive test. I only show percentages for years with at least 8 deer tested in each county. (The combined data from 1999-2001 is plotted at 2000.)
