Biostatistical Calculators for Scientific Research

Fast, reliable, and scientifically peer-reviewed statistical tools designed for clinical researchers, epidemiologists, and students. Computed instantly in your browser with zero data leakage.

Sample Size Tool Welch's t-Test
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Research Calculators

Sample Size Calculator

Determine optimal enrollment for two binary proportions or two continuous means with statistical power (1 − β) and significance level (α).

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t-Test (Welch & Paired)

Conduct hypothesis testing for two independent groups (Welch unequal variances) or matched pairs with exact p-values and Cohen's d.

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Chi-Square Test (2 × 2)

Evaluate categorical independence with Pearson's χ², Yates' continuity correction, expected counts verification, and Cramér's V.

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Odds Ratio & Relative Risk

Compute Odds Ratios, Relative Risk, Absolute Risk Differences, and NNT with exact 95% confidence intervals and Haldane zero-cell correction.

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Why Choose LabStats?

100% Client-Side Privacy

Clinical data protection is non-negotiable. LabStats operates entirely inside your local browser sandbox. Patient numbers, sample counts, and trial data are never transmitted over the internet.

Mathematical Precision

Every algorithm is verified against reference software (R and Python SciPy) using standard numerical approximations (Lanczos gamma, Acklam inverse normal, and Lentz continued fractions).

Publication-Ready Reporting

Each calculator generates formatted summary statements adhering to standard scientific guidelines (APA 7th edition and ICMJE) with one-click clipboard copying.

Frequently Asked Questions

Are LabStats tools free to use for academic publications?

Yes. All calculators on LabStats are free for academic, clinical, and commercial research. When publishing research assisted by our calculators, citing the specific statistical method referenced on the tool page is recommended.

How does LabStats handle zero cell counts in contingency tables?

In the Odds Ratio calculator, if any cell equals zero, our engine automatically applies the Haldane-Anscombe correction (+0.5 added to all four cells) to avoid mathematical singularities while maintaining asymptotic properties.

Does LabStats require an active internet connection?

Once a calculator page has loaded, all calculations execute locally via JavaScript. You can disconnect from the internet or work offline, and the calculators will continue to function seamlessly.

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