For those of you who choose not to take part in the study, we will use your de-identified information (this means that names and addresses are removed) to help us to understand how representative the study is of the wider population, to see if certain groups are more or less likely to participate in the study and to adjust the results of statistical analyses to better reflect the wider population. In Northern Ireland, the data will be accessed securely via the Honest Broker Service, a safe setting hosted by the HSC Business Services Organisation. If you prefer us not to retain or use your data for this purpose, you can contact us and ask us to delete your data – see ‘Contact details of the data controller’.