MethodVahti · Qualitative sampling
Defend the sample you can actually recruit.
A reviewer asks why twelve interviews were enough. An ethics committee wants the planned number. Your pilot data has made the original plan look optimistic. MethodVahti turns the study you have into a sampling range, a written rationale, and a record of the judgment behind both.
What is the correct N?What makes this N defensible?
Runs in your browser · nothing uploads · you make the research decision
Start with the problem you have
Choose the situation. MethodVahti asks for the design details that matter there, instead of making you translate your study into a generic calculator.
“I’m writing the protocol and need an N I can defend.”
- You get
- A planned N as a range from three models, a saturation expectation, and the methods paragraph for your protocol.
- It asks
- Your orientation, how varied the sample is, target analytic depth, and any pilot signal.
- Our stance
- A defensible range with the reasoning, not a single magic number.
What you leave with
Not a score to paste into a paper. A methods argument you can edit, question, and take responsibility for.
A reasoned range
Three models shown together, with the assumptions and sensitivity visible.
Methods wording
Draft text for a protocol, ethics application, manuscript, or reviewer response.
A decision record
The study details, constraints, stopping rule, and human judgment behind the final choice.
COREQ and SRQR help structure what you report. They do not certify that the sample was adequate.
The defensibility profile
Sample size is one decision among several a reviewer will probe. The profile rates each design dimension Strong, Adequate, or Limited, and the overall judgement follows the least defensible dimension. Strengths do not offset weaknesses, the same way risk-of-bias tools work.
| Dimension | Judgement |
|---|---|
| Research question | Strong |
| Sampling | Limited |
| Data collection | Adequate |
| Analysis | Adequate |
| Reflexivity | Strong |
Overall defensibility: Limited — set by sampling. There is no overall number, on purpose: a single score would hide exactly the weakness a reviewer will find, and the distances between dimensions are not known.
Disagree with where the rule lands? Override it, in writing. A documented departure is defensible; a quiet adjustment is not. The dimension judgements are yours throughout, the tool orders them, it does not make them.
The profile template ships in the Sample Defence Pack (v1.1, a free update for existing buyers). The classification itself is open source in the methodvahti module.
Try the reasoning first
The free tools run locally in your browser. They are useful on their own and show how MethodVahti thinks before you buy anything.
€49 · one payment
Take the full decision record with you
The Sample Defence Pack is for the point where exploring is no longer enough and the reasoning has to survive a protocol, manuscript, or reviewer.
- Sample Defence Builder: a six-step local HTML tool.
- Adequacy log: recruitment, coverage, stopping decisions, and planned-versus-achieved reconciliation.
- Methods and response templates: editable Markdown, a worked example, and a concise terminology guide.
- No subscription: download it, keep it, and work offline.
It never states that saturation was reached for you. Fourteen-day refund if the pack does not give you a clearer sampling section.
For doctoral schools and research teams
Use the same sampling record across a project, let supervisors review the reasoning, and keep each revision visible.
Ask about a team licenceWhat MethodVahti does not decide
It does not certify that your sample is adequate, declare saturation, infer causality, or judge the quality of the study. The modelled range is decision support. You decide the sample and defend the reasoning.
The sampling-heterogeneity model is a Vahtian hypothesis and is not yet externally validated. Design defensibility is a separate question: MethodVahti reports it as an ordinal judgement with the full dimension profile, never as a number: RoB 2 and AMSTAR 2 do not sum their domains, and neither do we. The assumptions, coefficients, and validation plan are open.
Read the method, not a product FAQ
The fuller explanations belong in Learn, where they can be read and cited without sitting inside a sales page.