The surveys you receive are usually looking for the specific opinions of a very set group of people. If we don’t already know this information we will ask a few questions at the start of a survey to make sure that it is relevant to you. If it isn't you may be 'screened out' or get a message that you haven't qualified for the survey on this occasion.
Rather than consuming your time on answers that cannot be used the survey finishes early (normally within the first few questions).
This can happen from time to time, even if you have originally been selected to take part, as some surveys require more specific information than the system can initially provide.