New fiancée formula for marriage

Anthony Dooley
Thursday, 11 February, 2010

Women of the world, beware: men now have a new reason to avoid marriage commitment - the "theory of optimal stopping".

Just in time for Valentine's Day, UNSW statisticians have used probability theory to devise a formula to help Australian men decide the right time to choose a bride.

The question of when to pop the question has long vexed bachelors. But the new formula cuts the guesswork by using the theory of optimal stopping - a sequential decision-making process used in finance and medical trials to pinpoint when to take an action to maximize expected rewards and minimize costs.

"Probability isn't the most romantic basis for a marriage but while the formula won't fit everyone it does seem to fit a lot of couples, whether through accident or design," says the Head of the UNSW School of Mathematics and Statistics, Professor Anthony Dooley.

"The Marriage Problem is well known to mathematicians: basically comes down to working out how long you're prepared to wait to marry and how many marriage prospects you're likely to meet during that time. Our formula tells you the optimal age at which to propose and so have the highest probability of achieving your goal.

"One could argue that the current, less-structured approach to picking a marriage partner hasn't been 100% successful, so perhaps it's time for men to consider following a stricter set of rules when it comes to marriage planning. As well as meeting the right girl, they could also find themselves developing a new love for numbers - a win-win for everyone."

UNSW statistician Professor Bruce Brown wrote the formula as an offshoot of more serious research and has calculated that it gives men a 37% success rate of finding the best partner from a pool of marriage prospects - not bad odds given the divorce rate is predicted to rise as high as 50% for current brides and grooms.

"Maths helps us understand the world and how seemingly arbitrary actions actually add up into patterns - from relationships right through to robotics," says Professor Dooley.

"Although we devised this formula as a bit of fun in the latest edition of our magazine for high school students, Parabola, we hope it will draw attention to our ongoing research into statistical optimisation and help students to appreciate the calculations that go into everyday decision-making."

The full media release and formula are here.