Seeing Theory: A Site That Explains Probability and Statistics with Visual Animations

What the website is

Seeing Theory is a website that shows basic ideas about chance and statistics in a visual way. You can click, drag, and move sliders to see how the pictures change. It uses D3.js, a JavaScript tool that draws charts and animations in a web browser. The site has six main chapters, from basic probability to regression analysis (finding patterns that connect one thing to another).

What the chapters cover

The chapters go step by step. Chapter 1 covers basic probability, such as expected value (the long-run average) and variance (how spread out the results are). Chapter 2 covers compound probability, including sets, counting, and conditional probability (the chance of something when you already know some other information). Chapter 3 covers probability distributions, which show all the possible results of an event and how likely each one is. Chapter 4 covers frequentist inference, Chapter 5 covers Bayesian inference, and Chapter 6 covers regression analysis.

Key facts

• The site has 6 main chapters.
• A fair coin has a 1/2 (50%) chance for heads and a 1/2 chance for tails.
• The expected value of a fair six-sided die is 3.5.
• Chapter 3 covers discrete distributions such as the Bernoulli, binomial, geometric, Poisson, and negative binomial, and continuous distributions such as the normal, t, chi-squared, exponential, F, gamma, and beta.

Why it matters

Probability and statistics can be hard to learn from formulas alone. Seeing Theory lets students watch the numbers change as they adjust the inputs. This helps them build an intuition, or a feel, for ideas like averages, randomness, and the central limit theorem (a rule that says averages of many random values tend to form a bell-shaped curve).

What to watch

• The article is also a plea for money: the GIGAZINE site says rising prices have made running its servers very hard, and asks readers for donations.
• Watch whether GIGAZINE can keep its servers running without splitting pages into more parts to increase page views.