Atherton H, Oakeshott P, Aghaizu A, et al. Use of an online questionnaire for follow-up of young female students recruited to a randomised controlled trial of chlamydia screening. J Epidemiol Community Health 2010;64:580–4. The citation in the following sentence should read: They may also be useful in younger populations. In 2008, 93% of people in the UK aged 16–24 had used the internet within the last 3 months, compared with 63% of people aged 55–64.⁶