Once the data from the questionnaires has been entered into the computer another range of checks becomes possible. Once again, checks can be made for completeness and accuracy. Where control questions have been used the computer can check one answer against another. The computer will also check whether the correct sections have been completed following filter questions. Finally, to test the reliability of the interviewers, interinterviewer comparisons are drawn by analysing the results from one interviewer against the results of the whole survey.