Table 1.

Details of the Natsal-3 survey questions used as outcome variables in these analyses of sexually experienced persons aged 16 to 44 years (unweighted N=8926, weighted N=7400).

Question wording	Timeframe; number of responses permitted	Response options	Respondents eligible for each survey question	Number eligible for each question, unweighted (weighted)
Have you sought help or advice regarding your sex life from any of the following sources in the last year?	During previous year; multiple responses	Information and support sites on the Internet;a family member/friend; self-help books/information leaflets; self-help groups; helpline; GP/family doctor; sexual health/GUM/STI clinic; psychiatrist or psychologist; relationship counsellor; other type of clinic or doctor; have not sought any help	Entire sample of the current study	8926 (7400)
Have you got contraception from any of these sources in the last year?	During previous year; multiple responses	Internet website;a a doctor or nurse at your GP’s surgery; sexual health clinic (GUM clinic); family planning clinic / contraceptive clinic / reproductive health clinic; NHS antenatal clinic / midwife; private doctor or clinic; youth advisory clinic (eg, Brook clinic); pharmacy/chemist; supplies from school/college/university services; over the counter at a petrol station/supermarket/other shop; vending machine; mail order; hospital accident and emergency (A&E) department; any other type of place (please say where); I have not got contraception in the last year	Those reporting use of any contraceptive methodb in the last year	7182 (5862)
When you were last tested for chlamydia, where were you offered the test?	Last occurrence; single response	Internet;a GP surgery; sexual health clinic (GUM clinic); NHS family planning clinic / contraceptive clinic / reproductive health clinic; antenatal clinic/midwife; private non-NHS clinics or doctor; youth advisory clinic (eg, Brook Clinic); School/college/university; termination of pregnancy (abortion) clinic; hospital accident and emergency (A&E) department; pharmacy/chemist; other non-health care place (eg, youth club, festival, bar); somewhere else	Those reporting chlamydia testing in the last year	2387 (1545)
Where were you tested? (the last HIV test if more than one)	Last occurrence; single response	Internet site offering postal kit;a GP surgery; sexual health clinic (GUM clinic); NHS family planning clinic / contraceptive clinic / reproductive health clinic; antenatal clinic / midwife; private non-NHS clinic or doctor; youth advisory clinic (eg, Brook clinic); termination of pregnancy (abortion) clinic; hospital accident and emergency (A&E) department; somewhere else	Those reporting HIV testing in the last year	802 (562)
Where were you last treated for [STIc]?	Last occurrence; single response	Internet site offering treatment;a GP surgery; sexual health clinic (GUM clinic); NHS family planning clinic / contraceptive clinic / reproductive health clinic; antenatal clinic / midwife; private non-NHS clinic or doctor; pharmacy/chemist; youth advisory clinic (eg, Brook clinic); termination of pregnancy (abortion) clinic; hospital accident and emergency (A&E) department; somewhere else	Those reporting having been told by a doctor / health professional that they had an STI in the last year	178 (117)

^a Internet response options.

^b Including condoms.

^c Separate questions were asked about the following infections: chlamydia; gonorrhea; genital warts; syphilis; Trichomonas vaginalis; genital herpes; nonspecific urethritis (NSU) or nongonococcal urethritis (NGU).