BROOKE GLADSTONE: From WNYC in New York, this is On the Media. I'm Brooke Gladstone.

BOB GARFIELD: And I'm Bob Garfield. This week, we are devoting our entire show to politics, seriously, because earlier this year a Supreme Court decision reversed campaign finance rules in place for decades, opening the tap on undisclosed campaign contributions, which, in turn flood the zone with advertising like never before. Much more on that, coming up. This campaign season, spending on political broadcast ads has exceeded a billion dollars, 250 million of which was spent in the last two weeks alone. Is it really worth it? This hour we'll consider how that money talks and how far we've come, or haven't, in a half century of television campaign ads.

BROOKE GLADSTONE: The bedrock belief in modern politics is that money corrupts. The axiom plays out from sea to shining sea, or from Michael Bloomberg to Arnold Schwarzenegger. We seem to like the idea, the elegant simplicity of the notion that money buys elections.

STEPHEN DUBNER: I will tell you this, Brooke. If you go on the air, as you’re doing here, and tell people that campaign spending matters much, much, much, much less in electoral outcomes than they think, people will hate you for it.

BROOKE GLADSTONE: [LAUGHS] Stephen Dubner is a journalist, coauthor of Freakonomics and host of the popular Freakonomics podcast. You have written about some research that your partner in crime, Steven Levitt, did back in 1994. Can you tell me about his methodology?

STEPHEN DUBNER: This was back when he was in graduate school, and as an economist in training he was doing a little bit of futzing around in the political science realm. And because he was manually typing in from the congressional record the names of candidates who ran against each other in years and years and years of Congressional races, he began to notice a pattern, which was that there were quite a few instances in which the two same candidates ran against each other repeatedly. And what Levitt found was that if you looked at the Congressional races where the same two candidates ran each other repeatedly, well, the appeal of the candidate presumably didn't change a whole lot – you'd have to control for incumbency and things like that – but what often did change was the amount of money that was spent. And what that allowed him to do was to try to isolate the causal effect of the money itself. How important is it to spend a lot more money? And the result was – I'll be honest with you, I found it to be rather shocking – you can double the amount you spend and raise your share of the vote by about one percent. Similarly, if you’re winning an election and you cut your spending in half, you'll lose only about one percent of the vote.

BROOKE GLADSTONE: Okay, but Steven Levitt drew a lot of his conclusions from a study done back in the mid-'90s. Hasn't the growing amount of campaign cash, and now the Citizens United Supreme Court decision, which opens the floodgates even more, doesn't that make a difference?

STEPHEN DUBNER: I would say two things about it. First of all, even though Levitt’s first study in this was several years back, similar studies and replications have been done since, and the findings are quite consistent. Also, even though the total this year for all Congressional and Senate races will be in the neighborhood of about two billion dollars – it sounds like so much, but compared to what? I mean, compared to GDP, even compared to –

[BROOKE LAUGHS] – compared to how much Americans spend on, I don't know, chewing gum, aluminum foil, iTunes downloads in one day, one week, it’s really a pitifully small amount, if you think about it.

BROOKE GLADSTONE: But compared to the rest of the world it isn't.

STEPHEN DUBNER: No, compared to the rest of the world, it isn't. It’s a good indicator of how rich a country we are that we can afford to flush two billion dollars down the toilet every year trying to influence elections when it’s almost inconsequential. Winning candidates do raise more money, but the relationship between the money and their winning, it’s just a correlation. It’s not causal. So imagine you'd go out onto the street and it’s raining really hard and everybody’s got an umbrella. And if you'd didn't know any better, you'd think, oh, man, those umbrellas are making it rain. If only those people would put away the umbrellas, the rain would stop. Right? That’s kind of the way people think about campaign spending and winning elections. The people who win do raise and spend more money, but the reason they have more money is because they're a more attractive candidate.

BROOKE GLADSTONE: In a moment we'll be hearing from political scientist Paul Freedman. He's researched the issue and concluded that the volume of ads in an election does have the power to sway a potentially decisive percentage of voters. Even if we can influence them a little, might that be enough in this 50/50 country of ours where an election can be decided on very slender margins? Maybe that hundred bucks might make a difference.

STEPHEN DUBNER: It might. And, you know, my doing a rain dance might make it rain too. Absolutely. And, you know, the more you believe it, the more you’re going to see signs that it’s true. And of course you’re going to find political consultants, of course you’re going to find professors of political science, too; you’re going to find candidates, every candidate, you’re going to find campaign managers who tell you the money is key. What I'm telling you is that if you actually use data to examine this question rather than polling, rather than the kind of received wisdom of political consultants and their kind of gut instinct, what the data show is that it’s just not true. Does that not mean that there might be a particular ad campaign on TV that really, really works more than the average? Absolutely that happens, and there are anomalies all the time. The problem is what we do with the media is we take anomalies and we report them, because that’s what news is. So you’re going to read somewhere in the next week or so the story about how one great ad turned the tide in some race, and someone who was trailing 51 to 49 roared back because of this TV ad and won 53 percent. First of all, it’s very hard to isolate the effect of that TV ad, and second of all, even if it’s true, that’s one race out of how many. And the fact is that if you look over the long stretch, you just don't find a causal relationship between spending and electoral outcome.

BROOKE GLADSTONE: Stephen, thank you very much.

STEPHEN DUBNER: My pleasure.

BROOKE GLADSTONE: Stephen Dubner is a journalist, coauthor of Freakonomics and new host of the Freakonomics podcast, which has made it into the top 10 on iTunes. We'll link to it, or you can find it at Freakonomicsradio.com.