Math May Tell Which Marriages Last
Calculus, More Than Chemistry, Predicts Future Divorce Rates
Feb. 13, 2004 -- "Chemistry" may get the credit as the foundation for a good relationship, but new research suggests that calculus may better predict whether it stays intact. Researchers say that a mathematical formula they devised can predict with at least 94% accuracy which couples will eventually divorce.
"We actually were at 100% accuracy for most of our study, but a few couples we didn't think would get a divorce based on our formula did, which lowered our accuracy," says mathematician James D. Murray, PhD, DSc, FRS, of the University of Washington and Oxford University. "Still, after testing it on 700 couples, it's incredibly accurate."
The formula, which will be officially presented Saturday at the annual of meeting of the American Association for the Advancement of Science, predicts future divorce rates based on positive or negative numerical scores given for specific expressions or comments made as couples discussed a point of contention while being interviewed by a marriage counselor.
"It could be about money, sex, in-laws, housing -- whatever," Murray tells WebMD. "We videotaped couples during a 15-minute conversation and then tracked scores based on their actions and reactions onto a graph, so it wound up looking like a jagged-lined, cumulative Dow Jones average stock report."
For instance, a roll of the eyes by one mate scored a negative 4 score; a nod indicting interest or well-placed use of humor when discussions got heated warranted a positive 4.
Add the scores and it comes to this bottom line: It's not whether a couple frequently argues that predicts their success. It's how they argue.
Masters and Disasters of Marriage
"When couples whose marriages are stable over time talk about an area of contention or disagreement, their discussions have five times as many positive comments or expressions as negative. In couples who eventually headed to divorce, ratio of positive-to-negative was 0.8 to 1," says psychologist John Gottman, PhD, a noted marriage expert who conceived the mathematical formula and enlisted Murray's mathematical skills to help develop it some 13 years ago.
The scores for these ratios are based on two coding systems that Gottman developed -- a checklist of 13 behaviors scored for the speaker, and nine behaviors that are scored for the listener on each turn at speech, in both contentious discussions as well as any type of conversation.