It is very frustrating to invest time and effort into a survey then get opted out mid-process or especially at the end of an interview. Please understand that each survey serves a specific purpose for each research company that we work with. For example, if the answers you provide are not consistent with the type of person they are looking to survey, the data will be excluded from the final results as a result, the survey will end.
These sudden exits are not always based on your demographic information and can be based on a set of responses you provided during the survey. For example, some surveys might ask you the same question twice to make sure that you are paying attention. Conflicting answers will result in a disqualification. The best way to make sure this does not happen is to pay close to the surveys you are completing and being as honest as possible.