Volunteer Corey Essler holds a sign for Rick Santorum, Monday, in Menasha, Wis. in 2012. (AP)

No one loves lawn signs more than political candidates. Political candidates love lawn signs because 1. They love seeing their name around, 2. They assume that the number of lawn signs they see somehow correlates to the level of support they enjoy and 3. They know that campaigns have lawn signs, and candidates are biased toward mimicking what winning candidates have done. Between 1984 and 2012, according to one study, use of lawn signs in campaigns quadrupled.

The problem with lawn signs, as any campaign manager would probably tell you, is that they are expensive, annoying, logistically tricky to distribute and — most importantly — don’t seem to do much of anything. Candidates like to feel as if they’re winning. Campaign managers like to know that they’re winning or at least making progress. So campaign managers like things that have either measurable effects on voters (like identifying targeted supporters) or demonstrated past effects (like advertising). Lawn signs don’t fit into either category. To a campaign manager, lawn signs are similar to randomly handing out fliers at a grocery store: a waste of time, money and energy.

Now there’s data out that, in the main, proves campaign managers right. Last October, we spoke with Donald Green, a professor at Columbia University who has done decades of work assessing the utility of various methods of voter outreach. He's also the lead author of a study released this month that evaluates the efficacy of lawn signs. Green partnered with researchers at universities in Upstate New York, Pennsylvania and Virginia to test signs in four races at the federal, state and local level.

Cutting to the chase: “[I]t appears that signs typically have a modest effect on advertising candidates’ vote shares — an effect that is probably greater than zero but unlikely to be large enough to alter the outcome of a contest that would otherwise be decided by more than a few percentage points.” The effect of such signs, the study suggests, is about the same as direct mail.

Of the researchers’ four experiments, only one involved what you might generally think of as yard signs. In three of the experiments, signs were placed in public places within randomly assigned precincts. In the fourth, signs were placed in supporters’ yards — the thing that campaigns often spend a lot of time coordinating. In that case, interestingly, the effects were essentially zero. Aggregated, the four experiments suggested that there was a 1.7 percentage-point boost to the candidate from the signs -- with a standard error of 0.7 percentage points. (In precincts adjacent to the targeted ones, there was a slightly smaller benefit.)

(Green, et. al.) (Green, et. al.)

(The study included a sign, at right, paid for by FreedomWorks and used in the most recent Virginia gubernatorial election, which unfortunately misspelled the name of the state.)

In how many races would that sort of lawn-sign bump make a difference? Of 6,000-plus general and primary elections in House and Senate races between 2006 and 2012, only 2.2 percent of races were within 1.7 percentage points, according to our analysis of initial results. In other words, this could matter in 1-in-50 races.

The study also offers a result that candidates will love and campaign managers will hate. The effect is very small, but it would be hard for a campaign manager who's arguing for robust get-out-the-vote efforts to say no to a candidate who demands lawn signs in order to boost his margins. The silver lining is that the study suggests that the much-easier distribution of lawn signs in random public places is more effective than finding supporters and plunking signs in their yards.

But when have candidates ever sat down and considered the political science before making judgment calls in close races? Superstition dictates lawn signs, and candidates are the ones raising the money and putting their name on the ballot. The study would essentially have had to demonstrate that candidates who used them lost before a candidate would have second thoughts about the efficacy of lawn signs. And even then, he'd probably still buy them.