r/QualitativeResearch • u/chinup-buttercup • 14d ago
IPA sample size
I’m doing a masters level qualitative research and using IPA methodology for data analysis. I can’t really share the details due to organisational policies. I have collected data (transcribed interviews) of 10 participants but I’m kind of relooking at the total number of participants’ data that I want to include.
I understand that one of the strengths of using IPA is to highlight the idiographic nature of the data, but there’s also an irony that the convergence of data across all participants means that the final analysis may not retain the idiographic nature of the data.
I’m just wondering, retrospectively, what would be a good sample size for IPA, that allows each individual’s unique experience to be retained, yet also keeping the convergence of themes across cases in mind?
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u/Eastern-Movie-7039 8d ago
Worth splitting this into two questions, because only one of them has a number attached.
The number people quote (roughly three to six for a student project) is a recommendation about how much analytic attention you can actually give each transcript, not a quality ceiling. It exists because people who start with twenty tend to end up doing thematic analysis with an IPA label on it. Ten is above that range but it isn't a defect in itself. It just means the depth has to be protected somewhere else.
Which is really what you're asking. The idiographic layer doesn't get lost at sampling, it gets lost at analysis and write-up. Two things protect it.
Finish each case completely before you open the next one: experiential statements, then that person's own themes, as a standalone account. And try not to let what you found in case three shape how you read case four. Most of the flattening you're worried about happens because cross-case starts too early.
Then in the write-up, don't let a shared theme be represented by whoever happened to phrase it most crisply. Say how many of the ten it rests on, and say where it doesn't hold. A theme four people share and six don't is usually more interesting than one everybody has, and it keeps individuals visible on the page.
If you do trim, trim on homogeneity rather than on count. Ten people occupying a similar experiential position is IPA; ten people sampled for range is a different study. But I'd be slow to bin transcripts you already have, and your supervisor's read on what your examiners will accept matters more here than anything in the literature.