title: Men who have sex with men in Great Britain: comparing methods and estimates from probability and convenience sample surveys.
abstract: To examine sociodemographic and behavioural differences between men who have sex with men (MSM) participating in recent UK convenience surveys and a national probability sample survey.
  
  
  
  We compared 148 MSM aged 18-64 years interviewed for Britain's third National Survey of Sexual Attitudes and Lifestyles (Natsal-3) undertaken in 2010-2012, with men in the same age range participating in contemporaneous convenience surveys of MSM: 15 500 British resident men in the European MSM Internet Survey (EMIS); 797 in the London Gay Men's Sexual Health Survey; and 1234 in Scotland's Gay Men's Sexual Health Survey. Analyses compared men reporting at least one male sexual partner (past year) on similarly worded questions and multivariable analyses accounted for sociodemographic differences between the surveys.
  
  
  
  MSM in convenience surveys were younger and better educated than MSM in Natsal-3, and a larger proportion identified as gay (85%-95% vs 62%). Partner numbers were higher and same-sex anal sex more common in convenience surveys. Unprotected anal intercourse was more commonly reported in EMIS. Compared with Natsal-3, MSM in convenience surveys were more likely to report gonorrhoea diagnoses and HIV testing (both past year). Differences between the samples were reduced when restricting analysis to gay-identifying MSM.
  
  
  
  National probability surveys better reflect the population of MSM but are limited by their smaller samples of MSM. Convenience surveys recruit larger samples of MSM but tend to over-represent MSM identifying as gay and reporting more sexual risk behaviours. Because both sampling strategies have strengths and weaknesses, methods are needed to triangulate data from probability and convenience surveys.
authors.affiliation: Research Department of Infection & Population Health, University College London, London, UK.
authors.forename: Philip
authors.initials: P
authors.lastname: Prah
authors.affiliation: Sigma Research, London School of Hygiene & Tropical Medicine, London, UK.
authors.forename: Ford
authors.initials: F
authors.lastname: Hickson
authors.affiliation: UCL Institute of Education, London, UK.
authors.forename: Chris
authors.initials: C
authors.lastname: Bonell
authors.affiliation: MRC/CSO Social & Public Health Sciences Unit, University of Glasgow, Glasgow, UK.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: McDaid
authors.affiliation: Research Department of Infection & Population Health, University College London, London, UK.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Johnson
authors.affiliation: Research Department of Infection & Population Health, University College London, London, UK.
authors.forename: Sonali
authors.initials: S
authors.lastname: Wayal
authors.affiliation: Research Department of Infection & Population Health, University College London, London, UK.
authors.forename: Soazig
authors.initials: S
authors.lastname: Clifton
authors.affiliation: Research Department of Infection & Population Health, University College London, London, UK.
authors.forename: Pam
authors.initials: P
authors.lastname: Sonnenberg
authors.affiliation: HIV/STI Department, Public Health England, London, UK.
authors.forename: Anthony
authors.initials: A
authors.lastname: Nardone
authors.affiliation: Research Department of Infection & Population Health, University College London, London, UK Department of Health Services Research and Policy, London School of Hygiene & Tropical Medicine, London, UK.
authors.forename: Bob
authors.initials: B
authors.lastname: Erens
authors.affiliation: Research Department of Infection & Population Health, University College London, London, UK.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Copas
authors.affiliation: MRC/CSO Social & Public Health Sciences Unit, University of Glasgow, Glasgow, UK.
authors.forename: Julie
authors.initials: J
authors.lastname: Riddell
authors.affiliation: Department of Social & Environmental Health Research, London School of Hygiene & Tropical Medicine, London, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Weatherburn
authors.affiliation: Research Department of Infection & Population Health, University College London, London, UK.
authors.forename: Catherine H
authors.initials: CH
authors.lastname: Mercer
mesh_terms: D000293:Adolescent; D000328:Adult; D001294:Attitude to Health; D007722:Health Knowledge, Attitudes, Practice; D006306:Health Surveys; D018451:Homosexuality, Male / Q000523:psychology / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D060728:Reproductive Health / Q000706:statistics & numerical data*; D012494:Sampling Studies; D012747:Sexual Partners; D012749:Sexually Transmitted Diseases / Q000453:epidemiology / Q000517:prevention & control; D019966:Substance-Related Disorders / Q000453:epidemiology; D006113:United Kingdom / Q000453:epidemiology; D047568:Unsafe Sex / Q000706:statistics & numerical data; D055815:Young Adult
keywords: GAY MEN; SEXUAL BEHAVIOUR; SEXUAL HEALTH