How is Oregon Motor Voter affecting different counties?

(This is a guest posting from Nick Solomon, Reed College senior in Mathematics)

One of our first assignments in our Election Sciences course was to take a look at the Oregon Motor Voter data and try and tease out any patterns we could find in it.

screen-shot-2017-02-26-at-7-50-11-pmI’ve always been interested in geographic statistics, so I decided to examine Oregon counties. This can be especially valuable because geography tends to to be a good proxy for making inferences about demographic variables we might not have access to, like income, race, or education level (none of these are accessible via the Oregon statewide voter registration file).

The figure displays party of registration among citizens registered via OMV.  It’s important to remember when looking at the graphic that the OMV process initially categorizes all citizens as “NAV” (non-affiliated voters), and citizens must return a postcard designating a party. As of January 2017, as shown on the left, 78% of registrants did not return the card, and only 11% decided to select a party. 

Bar plot of percent of voter registered via OMV by county


The county by county totals are fascinating. OMV voters constitute the highest percentage of registered voters in Malheur county. Many readers may recognize the name–the Malheur National Wildlife Refuge was the site of a 41 day standoff between law enforcement and a small group of occupiers.  

Malheur is located in the farthest southeast corner of the state. It’s rural, relatively poor, and much more Republican than the rest of the state. John McCain received 69% of the vote in Malheur in 2008. 

In an upcoming blog post, another student will be posting a map of this county by county visualization, and it’s apparent that a number of rural counties have high percentages of OMV registrants. 

At the recommendation of a few experts who looked at the graphic I decided to examine the percentage of OMV voters by county versus the total number of registered voters. This lets us get a sense of whether Malheur is an outlier caused by a very small sample size making the percentage value overly sensitive or if this is a number that we can trust.

A scatter plot of log county population and percent of voters registered via OMV

Here, the total number of voters is plotted on a log scale, as many counties have smaller numbers of voters, while the Portland metro area has many more.

The log scale allows us to get a better sense of any relationship between number of voters and percent registered by OMV without the few large numbers dominating the plot.

This graphic shows that there are quite a few counties of similar size to Malheur, and some that are even smaller. Furthermore, we see that Malheur is not very far from other counties of its size.

Finally, to my eye, there seems to be no meaningful relationship between these two variables, so I find myself concluding that Malheur county, along with Umatilla and Morrow and Curry and Coos are experiencing a much greater benefit in access to voter registration than some larger, more urban counties.

For those interested, these graphics were made with R and ggplot2. I’ll be posting on my personal blog with more details about how I made them.

Eventually, I hope to learn more I was also curious about hoe OMV might be affecting party turnout at the polls. Keep tuned for future updates!