Proposal, ethics and confirmation
Justify your sample size before your committee asks
The sample-size question comes up three times in a doctorate: in the proposal, on the ethics application and at confirmation. This kit gets you one defensible answer you can reuse at all three.
Most candidates can run a power calculator. What stalls them is everything around it: which effect size to trust, which settings to report, and what to say when the number is more participants than they can realistically recruit.
What you work through
- Pin down what you are poweringThe four parameters, the analysis the number is for, and what your programme and ethics board require.
- Pick a priori, sensitivity or compromiseTwo questions that settle it, including what to do if data collection has already started.
- Go from design to inputsTwelve common designs mapped to their test and the exact inputs each one needs.
- Set alpha, power and tailsEach choice justified, plus a planner for studies with several hypotheses.
- Find an effect size you can defendWhere estimates should come from, a candidate table, and the questions supervisors ask about each.
- Stress-test the estimateConvert between effect-size metrics, decide the minimum effect worth detecting, and test a pessimistic, expected and optimistic value.
- Run it once and record everythingA five-step routine and a settings log for your appendix.
- Cover your analysis familyPages for t-tests and ANOVA; correlation, regression and proportions; and clustered or repeated designs.
- Turn the number into a recruitment targetAllow for drop-out, unequal groups and clustering, then work back through how many people you must screen.
- Check you can actually recruit itThe feasibility test, and your options if the gap will not close.
- Qualitative and mixed strandsInformation power and a stopping rule for the parts no power analysis fits.
- Write the section and rehearse the questionsParagraph skeletons, a completeness check and the questions to expect at confirmation.
The Calculator & Log
The workbook that goes with the worksheets, for Excel or Google Sheets:
- Effect Size — every candidate estimate, converted between d, r, eta-squared and f
- Sample Size — inflation for attrition, allocation and clustering, to a recruitment target
- Settings Log — one row per calculation, ready for the appendix
- Feasibility — the recruitment rate you need against the rate you can achieve
- Reporting — ten elements of a complete justification, with what is still missing
Look inside
Low-resolution, watermarked previews of four pages.
Is it for you?
- Doctoral candidates writing the methods section of a proposal or an ethics application.
- Candidates heading into confirmation of candidature with a quantitative or mixed-methods design.
No calculation happens inside the kit: your usual calculator produces the number, and the kit covers choosing its inputs, recording them and writing them up.
Free to use alongside it: Free sample size calculator.
The Sample-Size Justification Kit — $12, one-time.
Kits for your other milestones
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Literature review chapter
The Scoping Review Protocol Kit
A protocol, search log, screening record and charting form for a thesis scoping review - so the chapter can be examined and the review published.
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Throughout the thesis
The AI Use & Disclosure Kit
Record, verify and disclose how you used AI tools in a thesis: your institution's rules, a data gate, a verification log and a disclosure statement.
$9 -
Publishing during candidature
The Journal Submission Kit
Checklists and a tracker for submitting a paper during your PhD: shortlist journals, check scope and legitimacy, build the package and track decisions.
$9 -
Examination
The Defence & Viva Kit
Prepare for your viva or thesis defence: a question bank by type, examiner dossiers, mock-viva scoring and a corrections tracker for after.
$15
Frequently asked questions
My supervisor gave me a number. Do I still need this?
Probably, if you have to defend it. Committees and ethics boards ask where the effect size came from and what settings produced the number; the kit turns an inherited figure into a documented one.
Which software does it work with?
Any. Desktop power software, R packages and web calculators all need the same inputs; the kit tells you which to collect, how to log them and how to report them.
Data collection has already started. Is it too late?
No. The kit routes a fixed sample to a sensitivity analysis - the smallest effect your sample can detect - which is the honest answer at that stage.
My project is qualitative. Is there anything for me?
One page: information power and a saturation stopping rule. If your study is entirely qualitative, this is not the kit to buy.
What do I get, and in what format?
One ZIP download: the kit as PDF in both US Letter and A4, and a workbook that opens in Excel or Google Sheets. Fill the PDFs in on screen or print them.
How do I get the files?
The download page opens as soon as Stripe confirms payment, and a copy of the link arrives by email. A link stays valid for two weeks and ten downloads, and a replacement can be requested below whenever you need one.
Who processes the payment?
Stripe. The receipt and download email come from the author's publishing imprint, GradSummit, which delivers the kits for this site. Your card details are never seen by us.
What if the files will not open?
Email us within two weeks of buying and we will fix it or refund you in full. A refunded purchase can no longer be downloaded.
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