Sen. Bernie Sanders (I-Vt.) casts his ballot in Burlington, Vt., on Nov. 6, 2012. (ANDY DUBACK/ASSOCIATED PRESS)

Michael McDonald is an associate professor of political science at the University of Florida. Peter Licari and Lia Merivaki are Ph.D. political science students at the school.

In modern campaigns, buzzwords like “microtargeting” and “big data” are often bandied about as essential to victory. These terms refer to the practice of analyzing (or “microtargeting”) millions of voter registration records (“big data”) to predict who will vote and for whom.

If you’ve ever gotten a message from a campaign, there’s a good chance you’ve been microtargeted. Serious campaigns use microtargeting to persuade voters through mailings, phone calls, knocking on doors, and — in our increasingly connected world — social media.

But the big data that fuels such efforts comes at a big price, which can create a serious barrier to entry for candidates and groups seeking to participate in elections — that is, if they are allowed to buy the data at all.

When we asked state election officials about prices and restrictions on who can use their voter registration files, we learned that the rules are unsettlingly arbitrary.

Contrast Arizona and Washington. Arizona sells its statewide voter file for an estimated $32,500, while Washington gives its file away for free. Before jumping to the conclusion that this is a red- state/blue-state thing, consider that Oklahoma gives its file away, too.

A number of states base their prices on a per-record formula, which can massively drive up the price despite the fact that files are often delivered electronically. Alabama sells its records for 1 cent per voter , which yields an approximately $30,000 charge for the lot. Seriously, in this day and age, who prices an electronic database by the record?

Some states will give more data to candidates than to outside groups. Delaware will provide phone numbers to candidates but not to nonprofit organizations doing nonpartisan voter mobilization.

In some states, the voter file is not even available to the general public. States such as South Carolina and Maryland permit access only to residents who are registered voters. States including Kentucky and North Dakota grant access only to campaigns, parties and other political organizations.

We estimate that it would cost roughly $140,000 for an independent presidential campaign or national nonprofit organization to compile a national voter file, and this would not be a one-time cost. Voter lists frequently change as voters are added and deleted.

Guess who most benefits from all the administrative chaos? Political parties and their candidates. Not only are they capable of raising the vast amounts of money needed to purchase the data, but, adding insult to injury, they sometimes don’t even have to. Some states literally bequeath the data to parties at no cost. Alabama goes so far as to give parties a free statewide copy for every election.

Who is hurt by this? Independent candidates and nonprofit organizations that want to run national campaigns but don’t have deep pockets. If someone like Donald Trump launched an independent presidential run, he could buy the necessary data without much difficulty. But a nonprofit focused on mobilizing low-income voters could be stretched thin.

The high cost of acquiring big election data effectively subverts democracy by privileging the major political parties and the wealthy over the public. In light of the fact that some states make their voter lists freely available, it’s hard to find any compelling reason to keep onerous prices and use restrictions in place. This data belongs to the public. The millions of voter registration records are of us, and we should have access to them.