Sample Size Estimator

A simple and interactive Streamlit app that estimates the sample size needed for A/B tests

Tests Supported

1. Proportion tests (2-sample z-test)
2. Difference in group means (2-sample t-test)

Launch the app on Streamlit

https://samplesizes.streamlit.app/

Features

✅ Choose between comparing conversion rates or means

✅ Customize:

• Baseline value
• Expected lift or delta
• Alpha level (significance threshold)
• Statistical power (e.g. 80%, 90%)
• Alternative hypothesis test (two-sided, smaller, larger)

✅ Clear Results:

• Required sample size per group
• Explanations
• CSV download of inputs and results

Main Python File

sample_size_estimator.py # Main Streamlit app

Running Locally

If you'd like to run it locally make sure you install the packages (see requirements file), download the sample_size_estimator.py file, and then run:

streamlit run sample_size_estimator.py

License

This project is licensed under the MIT License.

Author

Developed by A. C. Sanders 2025