Research & Academic Tools

Sample Size Calculator

Sample sizes for prevalence studies, means, proportions, case-control, cohort studies and RCTs.

Odds Ratio Calculator

Odds ratio with confidence interval, z-test and Fisher's exact p from a 2×2 table.

Relative Risk Calculator

Relative risk, risk difference, ARR, RRR and NNT with confidence intervals.

Diagnostic Accuracy Calculator

Sensitivity, specificity, PPV, NPV, likelihood ratios and diagnostic odds ratio with CIs.

NNT / NNH Calculator

Number needed to treat or harm, with absolute and relative risk reduction.

2×2 Contingency Table Calculator

Chi-square, Fisher's exact test, odds ratio, relative risk and attributable risk.

Mean, SD & SEM Calculator

Mean, standard deviation, standard error, median, quartiles and CI from raw data.

Confidence Interval Calculator

Confidence intervals for means, proportions, differences, odds ratios and relative risks.

P-value Calculator

Convert z, t, chi-square, F and r statistics into p-values.

Effect Size Calculator

Cohen's d, Hedges' g, Glass's Δ, r, eta-squared and effect size conversions.

Statistical Power Calculator

Power or required sample size for t-tests, proportions and correlations.

SD, SE & CI Converter

Convert between standard deviation, standard error and confidence interval.

Meta-analysis Effect Converter

Convert ratios, log effects, CIs, p-values, medians and SMDs for meta-analysis.

I² Heterogeneity Calculator

Cochran's Q, I², H², τ² and pooled estimates for a meta-analysis.

Leave-One-Out Meta-analysis

Re-pool a meta-analysis leaving out each study in turn to test robustness.

PRISMA Flow Diagram Generator

Create a PRISMA 2020 flow diagram and export it as SVG, PNG or PDF.

Reference Formatter (DOI to Citation)

Turn DOIs into APA, Vancouver, AMA, Harvard, Chicago, IEEE and MLA references.

Vancouver Reference Generator

Build Vancouver-style references for journals, books, chapters and websites.

DOI Extractor

Extract, clean and deduplicate DOIs from reference lists and flag malformed ones.

PMID Extractor

Extract PubMed IDs from text and links, remove duplicates and open them in PubMed.

Reference Duplicate Finder

Find duplicate references by DOI, PMID, exact and near-identical titles.

Journal Abbreviation Finder

Look up NLM and ISO journal title abbreviations, and expand abbreviations.

Citation Number Checker

Check numbered citations for gaps, order, ranges and uncited references.

CSV Descriptive Statistics

Summary statistics for every column in a CSV file: N, missing, mean, SD and more.

Missing Data Checker

Count and chart missing values per variable and find incomplete rows in a dataset.

Outlier Detector

Flag outliers with the IQR rule, z-scores or modified z-scores without deleting data.

Normality Checker

Shapiro–Wilk test, skewness, kurtosis, histogram and Q–Q plot for your data.