We are asking study members to complete a short web questionnaire to get your input on how we can make taking part in the study an enjoyable and interesting experience.
You will also be asked to check and update the contact details we hold for you, to help us keep in touch.
The survey should take about 15 minutes to complete.
It is being carried out by Ipsos MORI, an independent social research organisation, on our behalf.
As a thank you for taking part we will send you a £10 e-voucher.