Free tools for researchers
Free tools for citations and manuscripts. No account is needed, and nothing you type is stored.
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Sample size calculator
Work out how many participants you need to estimate a proportion or a mean, or to compare exposure in cases and controls.
Runs in your browser
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Power and sample size for two groups
Find the number of participants per group needed to compare two means or two proportions, or the power you get with a given number.
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Confidence interval from an estimate and its P value
When a paper gives an effect and a P value but no interval, recover the standard error and the confidence interval.
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Odds ratio and risk ratio from a 2×2 table
Enter the four counts of a 2×2 table to get the odds ratio, risk ratio and risk difference with confidence intervals.
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Sensitivity, specificity and predictive values
Enter the true and false positives and negatives of a test to get sensitivity, specificity, predictive values, likelihood ratios and accuracy.
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Number needed to treat (NNT) and to harm (NNH)
Calculate the NNT or NNH from the event risks in the control and treated groups, with a confidence interval when you give the group sizes.
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Cohen's kappa (agreement between two raters)
Measure how well two raters or two tests agree beyond chance, from a 2×2 table of their ratings.
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Cohen's d and Hedges' g from two groups
Turn the means, standard deviations and sizes of two groups into a standardised effect size with a confidence interval.
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Chi-square and Fisher's exact test for a 2×2 table
Compare two groups on a yes/no outcome: chi-square with and without Yates' correction, and Fisher's exact test.
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t test from summary data
Test the difference between two means, or a paired mean difference, from the numbers printed in a paper, without the raw data.
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Estimate mean and SD from median and quartiles or range
For a meta-analysis: estimate the mean and standard deviation of a study that reported only the median with quartiles or with the range.
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Laboratory unit converter (mg/dL and mmol/L)
Convert common laboratory values between conventional and SI units: glucose, lipids, creatinine, urea, uric acid, bilirubin, calcium, haemoglobin and HbA1c.
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Gestational age and due date calculator
Find the gestational age on a chosen date and the estimated due date from the last menstrual period, a known due date or an ultrasound.
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Randomisation list generator
Create a reproducible allocation list for a trial with simple or permuted-block randomisation, two to six arms and a seed you can publish.
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Random sample selector
Pick a simple random sample of record numbers from a numbered list, such as patient files, with a seed so the draw can be repeated.
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Age and sex table for "Table 1"
Paste a list of ages and sexes and get the first table of a paper: number, mean (SD), median (IQR), range, age groups and sex counts.
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Confidence interval for a proportion (Wilson)
Get the Wilson score interval, and for comparison the exact Clopper–Pearson interval, for a percentage such as a complication rate.
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Article title analyzer
Count the characters and words of your title, find abbreviations and check that your keywords appear in it.
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Structured abstract checker
Paste your abstract and see whether it has the four sections: Background, Methods, Results and Conclusion.
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Reporting checklist (CARE, STROBE, CONSORT, PRISMA)
Tick the items of the reporting guideline for your study design and save the checklist as a PDF to upload with your manuscript.
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Author contribution statement generator (CRediT)
Tick the CRediT roles of each author and get the contribution statement in the wording of the journal's title page template.
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Conflict of interest and funding statement generator
Write the conflict of interest and funding statements for the declarations, and find the official ICMJE disclosure form.
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Ethics statement generator
Fill in the committee, number and date and get the ethics and consent sentence for the Methods section.
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Abbreviation list extractor
Paste your manuscript text and get the abbreviations you defined, the ones you used without defining, and how often each is used.
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Figure resolution (DPI) check
Choose an image file and see its pixel size and its real resolution at the printed size, against the minimum dpi.
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Table to HTML and Word converter
Paste a table from Excel or a CSV file and get a clean table you can copy into Word and the HTML code of it.
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Is my paper within the journal's scope?
Answer a few questions about your manuscript and see whether it fits the aims and scope of the journal.
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Case report timeline builder
List the dates and events of a case and get the timeline table that the CARE guideline asks for, in date order.
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Chart colour-blindness checker
Enter the colours of your chart and see how they look to readers with red-green or blue-yellow colour blindness.
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Is this journal trustworthy? (Think. Check. Submit.)
A checklist for authors who want to check a journal before they submit, after the Think. Check. Submit. campaign.
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Abstract readability score
Get the Flesch Reading Ease score and school grade of an English abstract, or the Ateşman score of a Turkish one.
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Manuscript writing planner
Enter the day you start and the day you want to submit, and get a plan with a date range for each stage of writing.
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Response to reviewers table generator
Choose the number of reviewers and comments and get an empty point-by-point response table, ready for Word or a spreadsheet.
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Case report pre-check (CARE items)
Paste your case report and see which CARE items your text mentions and which it does not, with the words found.
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Submission file name checker
Check the names and formats of the files you are about to upload: spaces, special characters, length and accepted file types.
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Kaplan–Meier curve from a CSV
Paste follow-up times and events to draw a Kaplan–Meier survival curve, with censoring marks and the median, and download it as SVG.
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Forest plot from a CSV
Paste the estimate and confidence interval of each study or subgroup to draw a forest plot, and download it as SVG.
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ROC curve and AUC from a CSV
Paste a test score and the true class of each participant to draw the ROC curve, get the area under it and the Youden cut-off, and download it as SVG.
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DOI to citation (Vancouver, APA, AMA)
Turn a DOI into a ready reference in Vancouver, APA or AMA style, from the record the publisher deposited at Crossref.
Asks an open scholarly registry
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Find DOIs for a reference list
Paste up to 20 references, one per line, and get the DOI of each one that Crossref matches with confidence.
Asks an open scholarly registry
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Citation count of a DOI
See how many times an article has been cited according to Crossref and OpenAlex, side by side.
Asks an open scholarly registry
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ORCID publication list viewer
Enter an ORCID iD to see the public works list of that researcher, with DOIs and years.
Asks an open scholarly registry
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NLM journal abbreviation finder
Find the official NLM (MEDLINE) abbreviation of a journal by its ISSN or title, for Vancouver references.
Asks an open scholarly registry
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ISSN validator
Check that an ISSN is well formed and that its check digit is correct.
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Abstract word counter
Count the words, characters and sentences of your abstract and compare them with a word limit.
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PDF metadata viewer
Open a PDF in your browser and read its embedded title, author, subject, keywords, producer and dates.
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Citation style for Zotero and Mendeley
Download the journal's CSL style so Zotero, Mendeley and other reference managers format references the way the journal does.
Download