Free tools

Checks you can verify

Free, deterministic tools for clinical researchers — no account, no charge. The planning calculators run entirely in your browser with the rule or formula shown; the reference checker sends only the identifiers it finds and resolves them against the public registries. Every answer is something you (or your statistician) can check yourself.

Minimum detectable effect
You can enroll only so many patients. Given that n, what is the smallest true difference your study could reliably detect — and is it clinically meaningful?
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Which statistical test?
Outcome type, group structure, pairing, adjustment — answered as structured choices — mapped to an estimand-first primary analysis with its assumptions and fallback.
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Events per variable calculator
For chart-review and database studies where n is already fixed: given the events you have, how many covariates can a logistic or Cox model support before it overfits — the EPV 10 rule, with the arithmetic shown.
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Reference integrity checker
Paste your reference list — each cited DOI and PMID (up to 25 per run) is resolved against Crossref, the DOI handle registry, and PubMed, so a non-resolving or mismatched citation surfaces before a reviewer finds it.
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Abstract deadline tracker
Verified abstract-submission deadlines for research meetings across every specialty — browse by field, download a calendar entry, or get an email reminder before each deadline.
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The three planning calculators are the same deterministic engines that power RigorMD’s reviews — pure rule tables and closed-form formulas, no AI in the loop — exposed here for free. The reference checker is one layer of the $10 pre-submission review, which recomputes your statistics and appraises your methods across two independent engines on top of resolving every citation.

A check. These free tools flag what a design can and cannot detect, suggest an analysis to discuss, and report whether your citations resolve in the public registries — they are not a substitute for a qualified biostatistician. Have any sample-size justification, analysis plan, or reference list reviewed before you submit.