Question: Surely using a questionnaire would give demand characters so how do you know if your results are reliable?

Kirsty Miller answered on 13 Jun 2017:

Yes! Excellent point! That is one of the dangers of using a questionnaire – it can lead to socially desirable answers. However sometimes if you have a big number of participants, you don’t have any option but to use questionnaires – it would take up too much time, and be too difficult to interview hundreds of people!
There are some things we can do to try to reduce demand characteristics though: one is to make sure the questionnaires are anonymous. This is what I did in my study – the students completed their questionnaires on their own, there were no names on anything, they sealed their answers in envelopes and then put them in a huge box! This meant that they could be sure that no-one would know what their answer was! Some people actually wrote quite private things so I think that they felt quite confident that their answers were safe.
You are totally right though to think about that! Basically whichever method of data collection you use, it won’t be perfect, but the best thing to do is to choose the most suitable one, and then try to reduce the problems as much as possible!
Hope this helps, but any other questions, let me know! 🙂