We’ve chosen your address at random to make sure we get a truly representative picture of everyone in the UK. Your address can’t be replaced by anyone else, as this would bias the results. We chose your address from the Postcode Address File which is held by the Post Office and is available to the public. Because your address can't be replaced with another address, we rely on the goodwill of those who've been chosen to take part to make the study a success.

No. NDNS relies on voluntary co-operation. The more people who do take part, the more useful the results will be. Our interviewers feed back to us that people feel very positive about taking part in the survey, and so we hope that you will enjoy the experience. You can withdraw from the study at any time.

If you have recently received a letter asking you to take part, one of our interviewers will visit in the next week or so. We understand that you may be busy, so we’ll organise the interview at your home at a time that suits you. Your interviewer will ask you about a range of topics such as your eating habits, health and lifestyle and ask you to fill in a food diary for four days. We'll also ask you if you'd like to be interviewed by one of our nurses, who will take some measurements, like your blood pressure.

We will treat information you give in strict confidence under the Data Protection Act 1998, and we never pass on names or addresses. The results collected are used for statistical purposes only and will help inform the planning of future health services.

As a token of our appreciation you'll receive a £30 gift card and be offered personalised feedback if you complete a food diary. If you take part in the nurse interview we’re also be able to offer you gift cards worth up to £20, depending on which bits of the nurse interview you take part in .

We'd be happy to answer any questions you may have. You can email us on [email protected] or drop us a line using the freephone number 0800 652 4572.