True love in numbers

Math your way to the altar

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True love in numbers

Let’s make this very clear. We will not be talking about numerology cum astrology—the pseudoscience associated with the mysticism that certain numbers bring out natural patterns in the universe. Instead, we will talk real math—probabilities with permutation and combination—and see how it can solve problems often faced by lovesick people.

In 2010, Peter Backus wrote a research paper called Why I don’t have a girlfriend: An application of the Drake Equation to love in the U.K. His goal was to find out his chances in finding that one woman whom he could share his life with.

The Drake Equation by Dr. Frank Drake was theorized in 1961 to calculate how many intelligent alien civilizations exist in the Milky Way galaxy that we would be able to communicate with. Backus assumed that finding a girlfriend was as rare as meeting E.T., and so he redefined the parameters to know his chances of finding love in the U.K.

Let’s say you are a heterosexual adult male who wants to know your chances of finding a girlfriend in Metro Manila, with preferences similar to Backus’. Multiply all the values below to get the number of people who meet your criteria.

  • Population of Metro Manila
  • The fraction of people in Metro Manila who are women
  • The fraction of women in Metro Manila who live in Quezon City
  • The fraction of women in QC aged between 24 to 34
  • The fraction of women in QC aged between 24 to 34 who have college degrees
  • The fraction of attractive women in QC aged between 24 to 34 who have college degrees
  • The age of the male searcher

In Backus’s case, the equation yielded 10,510, which could be fewer if more stringent criteria were added. Eventually, Backus got married to the woman of his dreams. We don’t know which of the criteria he has compromised, but math does confirm that being choosy is the primary reason for being lonely.

Now, modify the equation above to know “bakit hindi ka crush ng crush mo.”

Math to pick The One

It is overwhelming to think about dating all the possible persons who match your criteria. Surely, there must be a mathematical formula to save you time and still land you The One.

The applicable theory for this comes from the famous mind tickler called the Secretary Problem written by Martin Gardner in February 1960 for Scientific American. The problem is rewritten as such to fit our discussion:

  • There is one vacancy for The One position.
  • There are n women available for you to date.
  • You should date the women in random order.
  • You must rank the women from best to worst without ties.
  • Once rejected, you cannot date that woman again.
  • You must propose to one woman only.

According to Gardner, the best way to solve this is to date the first 36.8 percent of the women on the list. You should rank them, but never propose to any of them. Then, date the remaining one at a time. As soon as you meet someone you like better than the best of the first batch, stop; you’ve found The One!

Of course, there is the possibility that there are better candidates you haven’t dated yet, but statistically, the odds will be in your favor. The 36.8 percent comes from Euler’s number e such that 1/e gives you approximately 0.367879. This number is used in compound interests, stock technical analyses, and optimal stopping techniques.

Estimate the number of wedding guests

For now, let’s all assume she said “yes,” and wedding bells are ringing. Married folks know how hard it is to come up with a wedding guest list. When you send out invites, you also need to indicate if kids and +1s are invited—and that makes it trickier. It would be easier if there weren’t any limiting factors such as budget and venue.

In the TED book The Mathematics of Love, Dr. Hannah Fry suggests a formula to estimate the number of guests attending your wedding.

01 Create a list of guests you’d like to invite and sort them by importance.
02 Determine the maximum number of people for each party.
03 Indicate the likelihood that they will RSVP with a “yes.” Consider old folks who might forget to RSVP but will certainly show up.
04 Multiply the numbers and keep a running total.
05 Cut off the list when the running total hits your threshold.

For instance:

#

NAME OF PARTY GUESTS YES PROBABILITY ATTENDANCE FACTOR

RUNNING TOTAL

1

Hazel 3 1.0 3 3

2

Mary Anne 3 0.9 2.7 5.7

77

Anj 2 0.33 0.67 100.27
TOTAL 127

Statistically speaking, on your wedding day, there could be at worst zero guests or a full capacity of 127. Prepare for the maximum number and wait for the RSVPs to see if you can invite others who didn’t make the cut.

Math is a logical way to find love in this world. Spock would surely have a better equation, but be warned: most great mathematicians followed their hearts for crazy reasons only they knew.

Words Val J. Gonzales
First published in Speed February 2016
Read more: Love at first swipe