Statulator is a free online statistical program that conducts statistical analyses, interprets the results and provides suggestions about reporting them. It can be accessed by clicking here.
It includes a suite of sample size calculators for six scenarios: estimating a single proportion, comparing two independent proportions, comparing paired proportions, estimating a single mean, comparing two independent means and comparing paired means.
All sample size calculators provide live interpretations of the estimated sample sizes in plain English. The text could be adapted for describing the approach for sample size calculation in journal articles, theses or technical reports.
All calculators have inbuilt visualizations that allow you to visualize the influence of changing input parameters on sample size estimates. These visualizations can be customized and downloaded as PDF files.
All sample size calculators also have facilities to create sample size tables for a range of input values which can be downloaded in Excel files at the click of a button.
Sample size calculators for comparing independent means and proportions also have functions for conducting equivalence, superiority and non-inferiority trials.
Here’s the website for Statulator: http://statulator.com/
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Note: Adapted from the article originally published on LinkedIn on May 8, 2015: https://www.linkedin.com/pulse/free-online-sample-size-calculations-visualizations-navneet-dhand/