Monday, April 22, 2013

The 12 Bonk Rule

I am on a mailing list from Business Insider and against my better judgement (which often comes out when the internet is involved) I followed a link to an article on The Sexiest Scientists Alive. There are 50 scientists listed, and scientist number 43 is Clio Cresswell, a mathematician at the University of Sydney, who is the author of Mathematics and Sex


The book gained some notoriety for propounding the 12-bonk rule. Bonking is a term in Australia for having sex (usually casual sex as I recall), and Dr. Cresswell has stated that the best strategy for finding a good (sexual) partner is to bonk with 12 twelve different partners, note the best one, then keep bonking until you find someone who is better, then settle on that partner. You benchmark on a sample of 12 partners, discard them, then take the next best that comes along. Cresswell reports that this strategy gives you a 75% chance of finding a good mate. So it's not foolproof, but with the confidence of mathematics, it proclaims to be better than any other trial-and-error approach that leaves behind a trail of discarded lovers. Of course there is more at play in finding a mate than "bonkability", as opined in the Ask Sam column of the Sydney Morning Herald for example.

The result caught my eye as I was recently reviewing some statistical problems and I surmised that the 12-bonk rule had a similar sounding result to the secretary problem, a classic problem in probability. The secretary problem (which by now should be at least upgraded to the executive assistant problem, or simply just the candidate problem) asks for the best strategy to select a secretary for a position where there is a collection of candidates and you get to have one interview, upon which you must either hire the candidate or move onto the next one. It is assumed that the market is competitive and that you will not be able to return to a rejected candidate as they have found employment elsewhere. 

The optimal strategy here is to interview 37% of the possible candidates, make a note of the best one, and then keep interviewing until you a find an additional candidate that is better than you previous best, and then choose the new best candidate as the one to employ. So if you have 100 candidates, interview the first 37, note the best, and then keep interviewing until you find someone better and then hire them. The graph below plots the probability of finding the best candidate using this strategy, as the percentage k of candidates interviewed and refused increases.



Here 37 is the double winner in that the point marked by the dashed lines indicates that the optimal approach is to reject the first 37% and then you will find the best candidate as the next best choice 37% of the time. This magic 37% is derived from 1/e = 0.37, where e is the base of the natural logarithms.

I just downloaded the e-book version of Mathematics and Sex and took a quick look at the 12-bonk section, and it seems that Cresswell's discussion is based on the work of Peter Todd in his paper Searching for the Next Best Mate. Todd looks at simpler heuristics to find a mate than applying the 37% rule, which he notes has the following drawbacks in practice. If we assume a sample of 100 people where they can be rated uniquely on a scale from 1 to 100, then when applying the 37% rule
  1. On average, 37 additional people need to be interviewed (or bonked) to find the next best beyond the best found in the initial 37 people, for an average total of 74 people being considered from the 100.
  2. On average, the best person found has rank 82, where 100 is the best on the scale. The 37% rule finds the best person 37% of the time, but averaging the success out over the remaining 63% of choices, lowers the result by about 20%.
Todd decided to explore other decision rules that performed better than the 37% rule on some criteria, and more closely match with our observed behaviours for finding a mate. It is unlikely that anyone will have the time and (emotional) energy to engage with 37% of all their potential mates, which could easily run into the thousands. Todd's computer models found that if you engaged 12 people from a mating population of 1000, then took the next best, you are highly likely to end up with someone in the top 25% of the population. I cannot quite tell from Todd's graph referring to this result as to how many people must be engaged in total, but seemingly around 30 or so (50 at the outside).

So this was the genesis of the 12-bonk rule, and I will read Crisswell's book a bit closer to see if she has teased out any further details or conclusions. A very quick search of the internet on the topic of the number of sexual partners seemed to indicate that for Western men and women 12 sexual partners is on the high side for most of them - actually more like half of that, after discarding "outliers". A further potential glitch in the 12-bonk rule is that it assumes when you have found your post-12-bonk lover that he or she will accept your overtures, and of course you cannot be certain of that. I am sure that someone is working on the mathematics of unrequited love. 

8 comments:

Packers And Movers Mumbai said...

really a very nice blog i really appreciate all your efforts ,thank you so much for sharing this valuable information with all of us
Packers and Movers Mumbai

Obat Asma said...

thanks for the information is very useful for me, as well as add new insight and knowledge..
OBAT BATUK
OBAT SINUSITIS
OBAT KOLESTEROL
OBAT ASMA
OBAT AMBEIEN

Packers Movers Bangalore said...

I must be thankful for sharing your ideas.Thank you for the good writeup.its a brelient job.please visit here for more detail:
Packers And Movers Bangalore charges

Packers Movers Jaipur said...

really a vry nice blog i really appreciate all your efforts ,thank you so mch for sharing this valuable information with all of us.
Packers And Movers Bangalore

nizith seo said...

It is common to find ourselves in situation where the dates to vacate your facilityis predetermined and you are not ready yet to move into the would-be facility. The situation may apply to both – home as well as office. In such situations, you could opt for our storage and warehousing services.
packers and movers satna
packers and movers bhilai
packers and movers in cuttack
packers and movers in durgapur
packers and movers in meerut
packers and movers rajahmundry
packers movers jodhpur
packers and movers kakinada
packers and movers korba
packers and movers dhanbad

nizith seo said...

packers and movers coimbatore
packers and movers in nashik
packers and movers in panchkula
packers and movers in zirakpur
packers and movers allahabad
packers and movers in amritsar
packers and movers mangalore
packers and movers bilaspur
packers and movers in ajmer
packers and movers pondicherry

nizith seo said...

Packing and unpacking is part and parcel of moving goods. Through our vendors you could get professional packing for the wide range of items for your home and office.
packers and movers thrissur
packers and movers in belgaum
packers and movers kharagpur
packers & movers in nagpur

nizith seo said...

For those who may not know about this might find it hard to imagine that international shipment of household goods is a very standard practice by now. We have truly become global citizens. There are statutory provisions in import and export regulations to deal with international relocations. You just need to opt for international relocation while filling out forms or while searching and you will be redirected only to relevant providers.
Packers and Movers in Bangalore
Packers and Movers in Pune
Packers and Movers in Mumbai
Packers and Movers in Hyderabad
Packers and Movers in Delhi
packers and movers in panchkula
Packers and Movers in Kolkata
Packers and Movers in Chennai