Statistics & Data
Discrete and Data
Data displays, center and spread, the normal distribution, correlation and regression, sampling and experiments, random variables, and the logic of confidence intervals and hypothesis tests.
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Pictures of Data
Unit 1 · Data and Displays
0 of 11 units complete
- 1Unit 1Data and Displays5 parts · about 14 min
Pictures of Data
Before any formula, draw the data. Sort variables into kinds, build dot plots and stem-and-leaf plots, read the shape of a histogram, and catch a graph that is lying to you.
- 2Unit 2Center and Spread5 parts · about 12 min
The Middle and the Spread
The mean is a balance point and the median is a halfway mark, and one billionaire can tell them apart. Measure spread with the standard deviation, find out why it divides by n − 1, and see what happens when you convert or rescale the data.
- 3Unit 3Percentiles and Box Plots5 parts · about 11 min
Boxes and Whiskers
Five numbers summarise a whole data set. Build box plots, fence off outliers with the 1.5 × IQR rule, work out what "90th percentile" really means, and compare two classes at a glance.
- 4Unit 4The Normal Distribution5 parts · about 13 min
The Bell Curve
Heights, test scores and measurement errors all pile up into the same bell shape. Compare apples with oranges using z-scores, learn the 68–95–99.7 rule, and read exact probabilities off the curve.
- 5Unit 5Two Variables5 parts · about 13 min
Two Variables
Drag points around a scatter plot and watch the correlation react. Race the least-squares line with your own, read residuals, see one rogue point wreck everything, and meet the films of Nicolas Cage.
- 6Unit 6Sampling and Experiments5 parts · about 12 min
Who Did You Ask?
The biggest poll in history got the election spectacularly wrong. Learn how samples go bad, the designs that keep them honest, why random samples still wobble, and what only an experiment can prove.
- 7Unit 7Random Variables5 parts · about 13 min
Random Variables
Give every outcome a number and chance becomes something you can average. Roll a thousand pairs of dice, decide which bets are worth taking, find out why standard deviations do not add, and meet a game worth infinitely much.
- 8Unit 8Binomial and Geometric5 parts · about 13 min
Counting Successes
Flip, shoot, guess: count the successes and the binomial distribution appears. Shape it with n and p, watch it turn into a bell, wait for the first six with the geometric distribution, and work out whether guessing can pass a test.
- 9Unit 9Sampling Distributions5 parts · about 12 min
Sampling Distributions
Take thousands of samples and stack up their averages: a lopsided population turns into a perfect bell. See how spread shrinks like 1/√n, why polls of 1000 people work, and why the casino always wins.
- 10Unit 10Confidence Intervals5 parts · about 13 min
Confidence Intervals
A poll says 52% ± 3%. Build that interval yourself, watch a hundred of them try to catch the truth, find out what "95% confident" really promises, and work out why national polls ask about a thousand people.
- 11Unit 11Hypothesis Tests5 parts · about 12 min
Is It Just Luck?
A friend's coin lands heads 16 times in 20. Suspicious, or just luck? Learn the logic of a test, what a p-value measures, the two ways to be wrong, and how testing twenty jelly-bean colours manufactures a discovery.