Sample spaces and the axioms
What is a probability a probability of?
Joe Blitzstein, Harvard
Free full course, textbook and problem sets. Exceptional teaching.
Core · Module 07
Probability is where careful people are wrong most often. Build it axiomatically and the paradoxes stop being paradoxes.
By the end of this module
You can reason correctly about uncertainty — including the cases where everyone's intuition fails.
What is a probability a probability of?
Joe Blitzstein, Harvard
Free full course, textbook and problem sets. Exceptional teaching.
How should evidence change what I believe?
Arbital
A guided, branching explanation that adapts to what confuses you.
Why do so few distributions describe so much?
Brown University
Every concept as a manipulable animation. Beautiful and genuinely useful.
Why is the bell curve everywhere?
Check yourself
Every answer comes with the reasoning, not just a verdict. Getting one wrong and reading why is the point.
01A disease affects 1 in 1000. A test is 99% accurate both ways. You test positive. Roughly what is the chance you have it?
02The central limit theorem requires that the underlying distribution be:
03Two events A and B are independent if: