# Weapon of Math Deduction: A Statistical Formula for Conflict Evaluation

IT’S NOT THE SIZE OF THE ARMY; it’s how you use it. That’s the conclusion of a recent study by Patricia Sullivan, a professor at the University of Georgia, who has devised a simple yet effective statistical formula that correctly predicts the outcome of 78% of the conflicts plugged into it.

Pr = probability that an intervening nation will achieve its goals
Limited goals mean better odds. Sullivan calculates the U.S.’s chances of success in Vietnam were 22%. The 1991 Gulf War had a 93% chance of succeeding. The invasion to overthrow Saddam had a 68% chance of working; as for routing insurgents and installing democracy, chances of success are 1 in 5.

x, y = variables
ß = magnitude and direction of variables’ effects
Sullivan’s formula has several variables, including war aims, troop levels, alliances, and length of conflict. She found that as troop levels increase, the probability of successfully achieving political aims through force decreases.

Pr(yi=1|xi) = 1/(1 + exp(-xi ß))

i = intervention in question
Sullivan tracked 122 military interventions involving the U.S., Russia, China, France, and the U.K. between 1945 and 2003. Overthrowing governments is easy, but using military intervention to get nations to do what you want has only a 17% chance of success. Propping up foreign regimes works just 40% of the time.

### AN IMPORTANT UPDATE

We’re falling behind our online fundraising goals and we can’t sustain coming up short on donations month after month. Perhaps you’ve heard? It is impossibly hard in the news business right now, with layoffs intensifying and fancy new startups and funding going kaput.

The crisis facing journalism and democracy isn’t going away anytime soon. And neither is Mother Jones, our readers, or our unique way of doing in-depth reporting that exists to bring about change.

Which is exactly why, despite the challenges we face, we just took a big gulp and joined forces with the Center for Investigative Reporting, a team of ace journalists who create the amazing podcast and public radio show Reveal.

If you can part with even just a few bucks, please help us pick up the pace of donations. We simply can’t afford to keep falling behind on our fundraising targets month after month.

Editor-in-Chief Clara Jeffery said it well to our team recently, and that team 100 percent includes readers like you who make it all possible: “This is a year to prove that we can pull off this merger, grow our audiences and impact, attract more funding and keep growing. More broadly, it’s a year when the very future of both journalism and democracy is on the line. We have to go for every important story, every reader/listener/viewer, and leave it all on the field. I’m very proud of all the hard work that’s gotten us to this moment, and confident that we can meet it.”

Let’s do this. If you can right now, please support Mother Jones and investigative journalism with an urgently needed donation today.

### AN IMPORTANT UPDATE

We’re falling behind our online fundraising goals and we can’t sustain coming up short on donations month after month. Perhaps you’ve heard? It is impossibly hard in the news business right now, with layoffs intensifying and fancy new startups and funding going kaput.

The crisis facing journalism and democracy isn’t going away anytime soon. And neither is Mother Jones, our readers, or our unique way of doing in-depth reporting that exists to bring about change.

Which is exactly why, despite the challenges we face, we just took a big gulp and joined forces with the Center for Investigative Reporting, a team of ace journalists who create the amazing podcast and public radio show Reveal.

If you can part with even just a few bucks, please help us pick up the pace of donations. We simply can’t afford to keep falling behind on our fundraising targets month after month.

Editor-in-Chief Clara Jeffery said it well to our team recently, and that team 100 percent includes readers like you who make it all possible: “This is a year to prove that we can pull off this merger, grow our audiences and impact, attract more funding and keep growing. More broadly, it’s a year when the very future of both journalism and democracy is on the line. We have to go for every important story, every reader/listener/viewer, and leave it all on the field. I’m very proud of all the hard work that’s gotten us to this moment, and confident that we can meet it.”

Let’s do this. If you can right now, please support Mother Jones and investigative journalism with an urgently needed donation today.