Lies, damn lies, and self-reported sexual activity statistics

According to “Womens Hour” on BBC Radio 4, Tuesday 30 Aug 2016

“a US study” said that people born after 1980 (ie under 35) are having “less sex than previous generations”.  The study was published in the journal Archives of Sexual Behaviour (a journal I know from my Psychology degree).  I believe this was the August 2016 study “Twenge, J.M., Sherman, R.A. & Wells, B.E. Arch Sex Behav (2016)”, found at the URL below.

As the quote from the study below shows, the above BBC description of the study findings was a simplification.  The trend was more pronounced for women, but nonexistent for Black Americans, and for all college graduates.

“Americans born in the 1980s and 1990s … were more likely to report having no sexual partners as adults compared to [those] born in the 1960s and 1970s … The shift toward higher rates of sexual inactivity … was more pronounced among women and absent among Black Americans and those with a college education.”

I have removed the obscure US slang terms for the different generations.

The data came from the US “General Social Survey” (GSS), from people aged 20-24, who were asked about their number of sexual partners since age 18.  Thus the data and the finding relates to the age range of 18 to 24.

According to the same radio programme, the UK National Survey of Sexual Attitudes and Lifestyles “appears to show a similar pattern” in the UK.  However this too was inaccurate.  The “NATSAL 3” 2012 study does indeed show a continuing small decline in the median number sexual encounters over the past 4 weeks, but that was in a sample of the UK population aged 16 to 44, not 18 to 24 as in the US study.  The UK age range is thus very different from that of the US study above, which makes a direct comparison with the US figures impossible.

This self-reported UK decline in median sexual activity is relative to previous higher figures from 1999, and still higher figures from 1990.  The study was set up around 1990 because of the need for accurate statistics on the topic due to the AIDS epidemic, so those are the earliest comparable figures.

“On average over the past two decades there has been a decrease in how often people [aged 16–44] say they have sex.”

According to the BBC radio programme’s description of the 2012 NATSAL3 study, “1 in 5 people aged 16-24 said that they didn’t have a sexual partner.”

In fact the 2012 NATSAL 3 study reported that 19.8% of people aged 16-24 had *never* had a sexual partner, not that they currently lacked one.  The sloppy wording on the radio programme suggested more sexual activity had been self-reported than was actually the case.

To summarise:

o In the USA only *some* categories of people reported having less sex (when aged 18-24) than those born before 1980, not the entire US age cohort (as the BBC alleged).

o Contrary to the BBC report, the available UK data logically *cannot* tell us whether the same thing happened here (because the UK NATSAL age range studied is much wider than the US GSS one).

o UK data does tell us that a different age range from the US study (16-44) have been reporting less sex in 1999 than in 1990, and less again in 2012.

o The UK 2012 NATSAL data also tells us that 19.8% of people aged 16-24 reported *never* having a sexual partner, not (as the BBC claimed) that they “currently” lacked one.

I’ll leave the last word on the more interesting question (“Why?”) to the BBC.