Key points at a glance
- Select participants for relevant experience and the research aim.
- Plan which similarities and differences you need to examine.
- Justify scope and limitations instead of relying on a universal minimum.
Who can help answer your research question?
A qualitative sample should provide access to experiences or perspectives relevant to the research question. Start by defining who has actually encountered the process you are studying. An easily available contact is not automatically a suitable participant.
Purposeful sampling uses substantive criteria to identify informative cases. Palinkas and colleagues describe several strategies for this kind of selection. Their discussion does not provide a universal prescription for every thesis; your strategy must fit your particular design.
Define eligibility and relevant differences
Begin with necessary characteristics, such as a particular experience or role. Then identify differences you want to represent deliberately. Demographic variables are not automatically relevant to every question. Explain why a characteristic may produce a meaningful difference in perspective.
Original example: You study students’ first experiences of a learning platform. Participants must have used it during their first semester. Previous platform experience and attendance at an induction may be useful selection dimensions. Dividing participants by subject alone is less convincing unless your question explains why that matters.
Separate selection from recruitment
The sampling strategy describes which cases you seek. Recruitment describes how you reach them. A classroom announcement, referral or institutional contact is an access route, not proof that the sample captures the relevant range of experiences.
Keep a short recruitment record covering eligibility, contact status and completed interviews. Limit personal details to what is necessary. If you mainly reach highly engaged volunteers, consider additional routes and explain the selection bias that remains.
Make invitations reflect the actual participation criteria. Do not promise particular outcomes or an interview duration you have not tested. Voluntary participation and understandable information should be built into recruitment.
Justify the scope and its limits
Plan a feasible sample around your question, case differences, interview depth and analytical workload. A small focused study needs a different justification from a comparison of several varied groups. Check early that you can analyse the proposed interviews carefully.
Do not claim saturation simply because you reached a planned number. If saturation belongs to your methodological approach, explain how you assessed it. In a fixed student-project timeframe, you can instead report the limited scope and its consequences transparently.
Final submission context
Formal details can feel like a separate writing task, but they matter just as much for a printed submission. Anything missing, misplaced or inconsistently formatted in the document will also appear in the bound copy.
Use this guide together with your cover page, table of contents, page numbers, source notes and appendices. Prepare the final PDF for printing and binding only after the complete file has been checked.
Practical check before PDF export
- Do headings, chapter structure and page numbers match?
- Are sources, figures and tables included completely?
- Are required elements such as declarations, appendices or the cover page included where required?
- Did you open and check the final PDF after exporting it?
Checklist
- Define the required experience.
- Justify intended differences between cases.
- Separate recruitment routes from sampling strategy.
- Allow time for detailed analysis.
- Report access gaps and limitations.
Common mistakes
- Interviewing only available acquaintances without substantive justification.
- Presenting one interview count as a universal scientific requirement.
- Claiming statistical representativeness from a small purposeful sample.
Print and bind your finished thesis
Once you have checked the content and final PDF, configure the printed copies to match your submission requirements.
Configure printing and bindingRelated content
Explore related guidance on thesis structure, sources, formatting and final submission.
Frequently asked questions
How many interviews do I need?
There is no universally appropriate number. The question, design, diversity and depth of analysis matter. Agree on a justified scope with your supervisor that you can analyse within the available time.
Can I interview people I know?
Potentially, if they meet the criteria. Reflect on existing relationships, inhibited responses and expectations. Personal access does not replace a defensible sampling strategy.
Is snowball sampling the same as citation chaining?
No. In snowball sampling, participants suggest other potential participants. Citation chaining follows links between publications. The purposes and limitations are different.