Statistics · Probability
Chapter 1 · 3
The idea
Calculating probabilities and sample space
Probability as the proportion of equally likely outcomes that are favourable; listing the sample space (including for two dice and two-way tables); the fact that probabilities of all outcomes sum to 1, and the complement rule P(A′) = 1 − P(A); and the difference between theoretical probability and experimental (relative frequency) probability.
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Statistics · Probability
Calculating probabilities and sample space
Probability as the proportion of equally likely outcomes that are favourable; listing the sample space (including for two dice and two-way tables); the fact that probabilities of all outcomes sum to 1, and the complement rule P(A′) = 1 − P(A); and the difference between theoretical probability and experimental (relative frequency) probability.
Why it works
Counting equally likely outcomes
A probability measures how likely an event is, on a scale from (impossible) to (certain). When every outcome of an experiment is equally likely,The list of all possible outcomes is the sample space. Getting the probability right almost always comes down to listing — or counting — the sample space correctly.
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