The Marriage Equation

A practical theory for predicting divorce and a scientifically-based marital therapy

James D. Murray
Emeritus Professor of Mathematical Biology
University of Oxford
&
Emeritus Professor of Applied Mathematics
University of Washington



The rise in divorce rates in developed countries is a widespread but poorly understood phenomenon. Previous attempts at predicting marriage dissolution tend to be based on mismatches in the couple's personality or areas of agreement; these have not been too successful. I shall describe a simple, but surprisingly predictive, mathematical model, based on only a few parameters describing specific marital interaction patterns. The mathematical model characterizes differences between different types of stable couples whose marriages are likely to last from two types of unstable couples. I shall show how a couple’s interaction data are collected, how their parameters are determined and what they predict for a couple’s marital future. In a 12-year longitudinal study on a large number of marriages the model predicted divorce with an accuracy of 94%. The work has helped us design new scientifically-based intervention strategies for troubled marriages which are proving encouragingly successful in clinical practice.