In 2006, Garth Sundem and I confronted one of the great unsolved mysteries in social science: Exactly how soon will a given celebrity marriage blow up?  Drawing on Garth’s statistical expertise and my extensive survey of the literature in supermarket checkout lines, we published an equation in The New York Times predicting the probability that a celebrity marriage would endure. The equation’s variables included the relative fame of the husband and wife, their ages, the length of their courtship, their marital history, and the sex-symbol factor (determined by looking at the woman’s first five Google hits and counting how many show her in skimpy attire, or no attire).  Now, with more five years of follow-up data, we can report firm empirical support for the Sundem/Tierney Unified Celebrity Theory.  The 2006 equation correctly predicted doom for Demi Moore and Ashton Kutcher; Pamela Anderson and Kid Rock; and Britney Spears and Kevin Federline. It also forecast that Will Smith and Jada Pinkett would probably not make it to their 15th anniversary, in December 2012; so far, they’re still married, but gossip columns are rife with reports of a pending split.  On a happier note, the 2006 equation identified two couples with a good chance to make it to their fifth anniversary, in 2010: Ben Affleck and Jennifer Garner, and Matt Damon and Luciana Barroso. Sure enough, they made it (and are still married).  As impressive as these results are, we believe even more scientific progress is possible. We have refined the equation by drawing on recent data as well as the research conducted by Garth in his fiendishly clever new book, “Brain Trust: 93 Top Scientists Reveal Lab-Tested Secrets to Surfing, Dating, Dieting, Gambling, Growing Man-Eating Plants, and More!”  While the 2006 equation did a good job over all of identifying which couples were most likely to divorce, some of the specific predictions proved too pessimistic. Because Demi was so famous — and much more famous than Ashton — we gave their marriage little chance of surviving a year, but they didn’t split until 2011. We were similarly bearish on Tom Cruise and Katie Holmes (because of his fame, his two failed marriages and their age gap), but they’re still together.  What went right with them — and wrong with our equation? Garth, a self-professed über-geek, has crunched the numbers and discovered a better way to gauge the toxic effects of celebrity. Whereas the old equation measured fame by counting the millions of Google hits, the new equation uses a ratio of two other measures: the number of mentions in The Times divided by mentions in The National Enquirer.  “This is a major improvement in the equation,” Garth says. “It turns out that overall fame doesn’t matter as much as the flavor of the fame. It’s tabloid fame that dooms you. Sure, Katie Holmes had about 160 Enquirer hits, but she had more than twice as many NYT hits. A high NYT/ENQ ratio also explains why Chelsea Clinton and Kate Middleton have better chances than the Kardashian sisters.”  Garth’s new analysis shows that it’s the wife’s fame that really matters. While the husband’s NYT/ENQ ratio is mildly predictive, the effect is so much weaker than the wife’s that it’s not included in the new equation. Nor are some variables from the old equation, like the number of previous marriages and the age gap between husband and wife.  In the fine tradition of Occam’s razor, the new equation has fewer variables than the old one. Besides the wife’s tabloid fame, the crucial ones are the spouses’ combined age (younger couples divorce sooner), the length of the courtship (quicker to wed, quicker to split), and the sex-symbol factor (defined formally as the number of Google hits showing the wife “in clothing designed to elicit libidinous intent”).  Why is the wife’s sexy image dangerous? And why do her variables — her image, her tabloid fame — matter so much more than her husband’s?  “You could explain this two ways,” Garth says. “Either the guy’s powerless to predict the marriage’s fate, or he’s an enigma, indefinable by numbers. I prefer the latter.”  But the former explanation seems more plausible to the experts I consulted, like John G. Holmes, a psychologist at the University of Waterloo in Ontario who studies relationships. “Women initiate 70 percent of breakups, so perhaps that’s why their personality and image are more predictive,” he says.  David M. Buss, who analyzed mating strategies around the world in “The Evolution of Desire” and “Why Women Have Sex,” suggests several reasons the wife’s sexy image and tabloid fame mean trouble.
How the Sundem-Tierney celebrity-marriage prediction equation measured up in its five years, and how it is being tweaked for added accuracy.