The findings from the third National Survey of Sexual Attitudes and Lifestyles (Natsal), which questioned 15 000 people aged 16 to 74, show that the proportion of women saying they have been victims of sexual coercion is more than double that of those who say they have been victims of rape.
Wendy Macdowall of the London School of Hygiene and Tropical Medicine, the lead Natsal author, said that education needed to address sexual coercion, which had become "normalised ... with rape at the extreme end of the spectrum".
Those surveyed were asked "whether anyone has ever actually made them have sex against their will" and 9.8% of women said they had, at an average age of 18. For men, the equivalent figure was 1.4%, according to the research, which is published in The Lancet.
Macdowall said there was a need for early intervention in schools to address the problem "before those gender stereotypes are developing" and because "somebody who has been victimised at a young age is much more likely to be victimised later".
The Natsal proportion is significantly higher than that in the most recent crime survey for England and Wales, which was based on interviews with people aged 16 to 59 and found that 3.8% of women had been the victim of a rape since the age of 16. But the definition of rape is narrower, requiring the perpetrator to "not reasonably believe" that the victim consents.
Macdowall said the discrepancy was because people did not always realise that a crime had been committed: "We know that people who have experienced what would meet the legal definition of rape do not describe it as such," she said. "We've always known police reports are the tip of the iceberg and there's always been the suspicion the crime survey figures are low."
In 15% of cases among women and men recorded by Natsal, the perpetrator was a stranger. Among female victims who were aged 13 to 15 when the event occurred, a family member or friend was responsible in nearly half of cases (45.2%), and for women aged 25 and older, a former or current partner was responsible in seven out of every 10 cases.
The responses confirmed huge under-reporting by victims – 12.9% of women said they had reported the matter to the police compared with 8% of male victims. Natsal, which interviewed people between September 2010 and August 2012, produced data on sexual behaviour, fertility, contraceptive use and sex-related diseases. The study follows previous ones in 1990 and 2000. But the most recent was the first to ask people about nonconsensual sex.
The age of first sexual experience, at 16, has remained the same as in the 2000 survey and the number of people having sex before the age of consent has not differed significantly either (31% of men and 29% of women).
The biggest changes since the first survey are in behaviour reported by women. When the first survey was carried out, men had had more sexual partners than women and though that remains the case, the gap is narrowing. Men used to have their first heterosexual experience at a younger age, but now it is the same for women. Additionally, although the number of men reporting same-sex partners has changed little from 1990, for women it has increased from 1.8% to 7.9% over the past 20 years. Researchers warned that this was not necessarily a result of female liberation but could be men demanding that women act out male fantasies of lesbian sex.
Meanwhile, the same survey has shown that the frequency with which Britons have sex has declined over the past decade, in what one researcher suggested could be a "recession impact".
On average, people aged 16 to 44 have sex just less than five times a month, compared with figures of 6.2 for men and 6.3 for women in 2000.
Professor Kaye Wellings of the London School of Hygiene and Tropical Medicine said the recession may have had an impact on the unemployed, but it may also have driven those in work to toil harder.
"There's a relationship between unemployment and low sexual function. That is to do with low self-esteem and depression. At the other end of the scale, iPads and computers have breached the boundary between the study and the bedroom." – © Guardian News & Media 2013
Haroon Siddique is a news reporter for the Guardian website.