MIT 18.05: Introduction to Probability and Statistics
18.05 is MIT's introduction to probability and statistics — probability models, random variables, Bayesian and frequentist inference, and regression — taught in a celebrated flipped, problem-centered format whose complete materials on OCW make it one of the most recommended statistics self-study courses anywhere.
Fennie is independent and not affiliated with MIT. This is an unofficial study guide.
Build my 18.05 study planWhat makes it hard
Probability problems punish plausible-sounding reasoning like no other subject — conditioning errors feel correct right up until the answer is wrong. The Bayesian-versus-frequentist arc in the second half is conceptually deep: computing both kinds of answers is easy, keeping their interpretations straight is the actual work.
What you'll cover
- • Probability models and counting
- • Conditional probability and Bayes' theorem
- • Random variables and distributions
- • Bayesian inference
- • Frequentist inference and hypothesis testing
- • Confidence intervals and regression
The 18.05 study guide
How to study for MIT 18.05, step by step.
- 1
Do the in-class problems, not just the readings
18.05's flipped design means the problem sessions are the course. Self-learners on OCW should work every class-slide problem cold before reading its solution — skipping them hollows the course out.
- 2
Write the conditioning explicitly, every time
Most probability errors are silent conditioning errors. Forcing yourself to write P(A given B) with both pieces named catches the mistake while it's still visible.
- 3
Keep a Bayesian-frequentist phrasebook
What a posterior probability claims versus what a confidence interval claims — write the interpretations side by side and revisit them each unit. The conceptual distinction is the second half's real content.
- 4
Simulate when intuition argues with the math
A ten-line simulation settles probability disputes instantly and builds the intuition for next time. The course's own materials model this habit — adopt it.
- 5
Run the schedule through Fennie
Upload the 18.05 outline from OCW and Fennie's Daily Plan paces readings, problem sessions, and psets to your timeline, with conditioning-trap quizzes and interpretation flashcards generated from the actual course materials. Free to start.
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How Fennie helps with 18.05
Fennie's Daily Plans pace 18.05's flipped rhythm — readings before problem sessions, psets after — for enrolled students and OCW self-learners alike. Chat through a conditioning argument that feels right but isn't, and drill the Bayesian-versus-frequentist interpretations the second half turns on.
FAQ
Is 18.05 good for self-study?
It's one of the best statistics courses on OCW — complete readings, problem slides with solutions, psets, and exams. The flipped format translates unusually well to self-pacing.
Is 18.05 hard?
The math is gentler than 18.600's, but probability reasoning itself is treacherous — conditioning errors feel correct. Problem volume, not lecture review, is what builds reliability.
18.05 or 18.600?
18.05 covers probability plus statistical inference at moderate mathematical depth; 18.600 is deeper, harder probability theory without the statistics. Data-science-bound students often want 18.05 first.
Pass 18.05 with a plan, not a cram
Upload your 18.05 materials and Fennie generates a Daily Plan paced to your deadline — plus chat, flashcards, and quizzes built from the actual course content.
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