Bayes’ Theorem Calculator

Interactive calculator for Bayes’ theorem with visualizations and real-world examples

Overview

The Bayes’ Theorem Calculator provides an interactive tool to understand and calculate conditional probabilities using Bayes’ theorem. Explore how prior beliefs are updated with new evidence to form posterior probabilities, a fundamental concept in statistics and machine learning.

Tips

  1. Start with pre-loaded examples: Use the medical testing or spam filtering scenarios to understand how Bayes’ theorem works before entering your own values.

  2. Vary the prior probability: Experiment with different base rates to see how dramatically they affect the posterior probability, even with accurate tests.

  3. Use natural frequencies: Convert percentages to actual counts (e.g., “out of 1,000 people”) to build better intuition about the results.

  4. Compare scenarios side-by-side: Test multiple prior probabilities or likelihood values to understand the sensitivity of your conclusions.

  5. Check extreme cases: Try setting values to 0, 1, or 0.5 to verify the calculator behaves as expected and deepen your understanding.