How We Found the Contributors Supporting Multiple 2016 Candidates

The NJ graphics team recently paired with National Journal Hotline’s EIC, Scott Bland, to create a couple stories using the ever-growing and always-dense Federal Elections Commission campaign finance data sets.

With this data, we analyzed which contributors donated to multiple campaigns during the past eight years — leading to some pretty interesting finds.

Our overall goal was to gain insight by comparing candidates — seeing how much their donor bases overlapped as a share of total 2016 donors and total 2016 dollars raised, and how much of the overall fundraising those donors accounted for.

This is the first time the NJ graphics team has shared one of our larger databases, making this resource available for our readers and colleagues across publications. (There is a link to data toward the end.)

To build this dataset, we pulled itemized individual contributions to campaigns and itemized transfers between committees made during the 2008, 2012, and 2016 presidential election cycles from the FEC’s bulk data repository. Uploading these tables to a MySQL database made making candidate-specific contributor lists much easier to comb through.

We then wrote a script in Node.js that joined each presidential candidate’s donor list to every other candidate’s, matching them against names and zip codes. (We took only the first two words of each donor’s name and shortened their zip codes to five digits, which helped eliminate discrepancies between otherwise-matching entries. However, because people move, change their names, or just sometimes enter different data with different campaigns, this match gives us a conservative estimate of repeat donors.) Summing the joined data gave us the total number of shared donors and the amount they gave to each candidate.

The script then outputted a crosstab/contingency table, matching candidates across the rows and columns. Below, you can see that Giuliani raised around 1.1% of his money from people who also contributed to Fred Thompson in 2008.

Here is the data.

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Here are a few other campaign finance stories as well. Thanks for reading!