For my thesis, I have created a development approach (consisting of schemes, an application template and prototype code) that should make it easier to develop and adapt applications for a specific platform.
I have conducted interviews with developers of that platform to evaluate my approach. There have been 5 interviewees so far and the feedback that I got from them is sufficient for my scope, I would say.
However, in my thesis I would like to justify my decision that 5 evaluators are enough. Is there any scientific research or paper that suggests a certain number of evaluators for such a rather theoretical approach?
I know Nielsen's work about heuristic usability evaluation which says that with 5 participants, you discover around 75% of all problems in software usability / UI testing.
But as I said, my approach is no specific software product that has to be evaluated, but only the model itself, which is why I'm looking for research in that area.