Karen O'Reilly

In my new book, Qualitative Research Methods for Everyone: An Essential Toolkit book, I confront the thorny issue of qualitative sampling (see earlier blog post), and I introduce the idea of initial, ongoing and final samples and of sample fitness rather than sample size 

What is sample fitness?

Interpretive sampling should fit with interpretivist logic, so instead of asking ‘is my sample the right size?’ we should ask ‘does the sample fit?’

Initial sample fitness should address fitness for the design stage of a project, ongoing sample fitness should be addressed in relation to the iterative-inductive design of the research, and final sample fitness should be assessed in terms of the claims made in final reports and other dissemination.

Initial sample fitness

Initial sample fitness asks: does the initial sample fit with the aims and objectives of the project? Here you do need to estimate size for costings and time but the number or size of the initial sample is far less relevant in terms of fitness than whether you have included the breadth of people (and other variables) to at least begin to address the aims and objectives. An initial sample should fit with the proposed methodology and methods, with the role of qualitative research in the entire project, with the location of the work in the literature review, with relevant practical and design issues, and with how rich and exploratory you wish to be. 

Ongoing sample fitness

Ongoing sample fitness asks how your continued selections and choices, including what methods to use, fit with the interpretivist logic of learning as you go. 

Final sample fitness 

Final sample fitness asks: does my final sample fit my conclusions? Do I have a good sample with which to talk about this with confidence? Does my sample or selection fit my claims?

More of all of this in the book. Thanks for reading!