Men who have sex with men in Great Britain: comparison of a self-selected internet sample with a national probability sample.
OBJECTIVE
To compare the characteristics of a self-selected, convenience sample of men who have sex with men (MSM) recruited through the internet with MSM drawn from a national probability survey in Great Britain.


METHODS
The internet sample (n = 2065) was recruited through two popular websites for homosexual men in Great Britain in May and June 2003. This sample was compared with MSM (n = 117) from the National Survey of Sexual Attitudes and Lifestyles (Natsal), a probability sample survey of adults resident in Great Britain conducted between May 1999 and February 2001.


RESULTS
No significant differences were observed between the samples on a range of sociodemographic and behavioural variables (p>0.05). However, men from the internet sample were younger (p<0.001) and more likely to be students (p = 0.001), but less likely to live in London (p = 0.001) or report good health (p = 0.014). Although both samples were equally likely to report testing for HIV, men from the internet sample were more likely to report a sexually transmitted infection in the past year (16.9% v 4.8%, adjusted odds ratio 4.14, 95% CI 1.76 to 9.74; p = 0.001), anal intercourse (76.9% v 63.3%; p = 0.001) and unprotected anal intercourse in the past 3 months (45% v 36.6%; p = 0.064).


CONCLUSIONS
The internet provides a means of recruiting a self-selected, convenience sample of MSM whose social and demographic characteristics are broadly similar to those of MSM drawn from a national probability survey. However, estimates of high-risk sexual behaviour based on internet convenience samples are likely to overestimate levels of sexual risk behaviour in the wider MSM population.
Evans
Alison Ruth
AR
City University, School of Social Sciences and Institute of Health Sciences, London, UK. alison.evans.1@city.ac.uk
Wiggins
Richard D
RD
Mercer
Catherine H
CH
Bolding
Graham J
GJ
Elford
Jonathan
J
D000293:Adolescent; D000328:Adult; D018451:Homosexuality, Male / Q000706:statistics & numerical data*; D006801:Humans; D020407:Internet; D008297:Male; D012494:Sampling Studies; D012747:Sexual Partners; D011795:Surveys and Questionnaires; D006113:United Kingdom / Q000453:epidemiology