Hi button! I am doing a PhD in clinical psychology which is mostly quantitative, but I am doing a small qualitative study as well, using semi-structured interviews which will be analysed using IPA (interpretative phenomenological analysis). I am aiming for up to 90 people in my quant study but just 8-10 people for the qual study, and this is perfectly acceptable in my field- most published studies of this kind using a clinical population have about 6-12 participants because the analysis is so rigorous and time-consuming, although of course there are some studies which are larger. I would think 10 should be fine although I would check with your supervisor what he/she thinks is a good number to aim for and of course it will depend on your population and how accessible they are as well. Best of luck, KB