Tag Archives: david spiegelhalter

Sex by Numbers: what statistics can tell us about sexual behavior by David Spiegelhalter #MRSlive @TweetMRS #MRX 

Live blogged at MRS in London. Any errors or bad jokes are my own.

  • What is sex? Only half of people think oral sex is sex which is why Clinton was not guilty of perjury
  • In 2012, 48% of babies were “illegitimate,” in 1973, one in twenty 16 year old got pregnant
  • For every 20 girls born, 21 boys are born
  • In 1938, at least half of brides under 20 were pregnant when they got married
  • The seven year itch is kind of true, that’s the peak of marriages lasting, after that familiarity keeps them going
  • Below is an awesome chart for a statistics book about sex 🙂
  • Report is that frequency of sex has fallen by 20% since 2000
  • Speaker asks that people don’t raise their hands regarding statistics 🙂
  • Sex is less frequent as people age
  • In a closed population, equal men and women, average number of partners should match, medians might differ but means must be the same, men report twice as many sexual partners as women report. Why? Maybe age mixing, maybe different definitions, maybe exaggerations and hesitancy
  • Men report more partners, and they report more even numbers and multiples of five, people round off the number (see second chart)
  • There is a social acceptability bias
  • Used the bogus pipeline to examine sex differences – a fake lie detector, fear of exposure applies more to women, pipeline caused women to give higher numbers
  • Women more likely to report same sex experiences and much more in recent years, men much less so
  • You have to separate behavior from attraction when discussing being gay
  • Panels can be used a rough ballpark but details are unreliable, 20% difference?
  • Alfred Kinsey collected 15000 sex history’s in the 40s and 50s
  • “When did you last have sex outside of your marriage” survey required active denial [what an awesome technique when applied appropriately!]
  • 17% o men brought up on farms had outlets with animals –> active denial led to more confessions [who know what is really true!]
  • Sphere Hite 1970s, 100 000 questionnaires went out but only 4000 completed so the results are dubious
  • [this dude is awesome! He’s critiquing the quality of research findings from old sex statistics. ]
  • Finally had decent data in the 1800s with civil registrations
  • How many boys are born per girls – it’s actually about 105 boys per 100 girls, more boys are born in wars? More boys if higher coital rates, early conceptions, conception not at time of peak-fecundity


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