Hi Rob,

If you want to use GT, I would strongly recommend Kathy Charmaz (2014) Constructing Grounded Theory.  For me it brought GT together in the clearest and most practical way.  

Chapter 4 Interviewing in Grounded Theory includes a section on "Theoretical Sampling", and there is a section entitled " How Many Interviews". 

I feel sure that this will be beneficial to you.

Kind regards

sylvia

I agree with both Katherine's doubts about setting sizes for samples in GT and Sylvia's recommendation of Charmaz's book. In particular, having different stakeholder groups to compare should help with the process of theoretical sampling.

Distinguishing stakeholder perspectives and insights will be important. One can only really get a sense of the appropriate number of interviews to conduct in the field — as one finds 'saturation point' (when no/little new data is being raised by participants). As a small Masters thesis too you seem to be constrained by time and that will be a limit you will need to reflect on in your method section. For instance, if you know you can only do 20/25 interviews then you can advise in terms of your 'future research' suggestions how many might be more appropriate. if you like your research you can continue to do more as part of a follow up research project.