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Flip to reveal answersWhat does the p-value of a hypothesis test measure?
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All 8 Flashcards — t-tests and z-tests
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Question
What does the p-value of a hypothesis test measure?
Answer
The probability of getting data at least this extreme if H₀ were true. Small p = the data are surprising under H₀.
Question
State the decision rule for a hypothesis test.
Answer
p < α → reject H₀; p ≥ α → fail to reject H₀ (α = significance level).
Question
When do you use a z-test vs a t-test?
Answer
z-test when the population σ is known; t-test when σ is unknown (you only have the sample sd) — the usual case.
Question
One-sample vs two-sample test?
Answer
One-sample: compare one group's mean to a fixed claimed value. Two-sample: compare two independent groups' means.
Question
When is a test one-tailed vs two-tailed?
Answer
One-tailed for a directional H₁ (μ < or μ >); two-tailed for H₁: μ ≠ (a difference either way).
Question
What is a paired (matched) t-test for?
Answer
When the same subjects are measured twice (before/after). Test the mean of the differences d: H₀: μ_d = 0.
Question
Why must you never say you 'accept H₀'?
Answer
A test can only fail to find evidence against H₀ — absence of evidence isn't proof. Say 'do not reject H₀'.
Question
Where do the final marks in an AI hypothesis-test question usually sit?
Answer
In the in-context conclusion — naming the real quantities (bottles, runners…), not just 'reject H₀'.
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Full study notes for t-tests and z-tests
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t & z tests, errors (HL only)
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