How can I trust my interiewee ?
On-line could give an edge to trusting the interviewee. Friendliness and communication could change the podium.
When doing an interview, the interviewer or the surveyor often faces a problem which can be crucial to the overall outcome of the research report. This question of "can I trust my interviewee?" becomes even more crucial when the interview is a face-face one.
When this is really an important issue for the interviewer, it does not really change anything to the interviewee as the interviewer can not decide or even perfectly judge which answer is correctly answered by the interviewee. However, there are a lot of different approaches that the interviewer can take and couple of things that can be done to psychologically motivate the interviewee for a better trust-able satisfactory answer.
One approach that can be done is taking the interview on-line than face to face. Making sure that the interviewee can trust the interviewer by being friendly and giving enough information to the interviewee, might ask before answering any questions. However, one must never push the interviewee over an answer because then he/she might keep a strong hold in protecting his liberty and follow up answers could have a negative impact.
Then, if possible, instead of interviewing one group it is better to interview several groups of people in different ways. This gives the interviewer an option to judge the percentile of errors in the answers.
Communication plays a big factor too in getting the correct answers since communication is power. The interviewer must be a friendly person and should not make the interviewee uncomfortable. So, the answer is...NO, we can never trust the interviewee completely but we can always make them motivated to answer better by taking some psychological steps. Communication is power !
Your idea/solution in one sentence: Don't trust the interviewee blindly, keep suspicion and make several interview groups.