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Statistics · Hypothesis testing

Chapter 1 · 4

The idea

Setting up a hypothesis test

The language and structure of a binomial hypothesis test: the population proportion p, the null hypothesis H0 : p = p0 and the alternative hypothesis H1, deciding between a one-tailed (p < p0 or p > p0) and a two-tailed (p ≠ p0) test from the wording, the test statistic X ~ B(n, p0) under H0, and what the significance level means.

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Statistics · Hypothesis testing

Setting up a hypothesis test

The language and structure of a binomial hypothesis test: the population proportion p, the null hypothesis H0 : p = p0 and the alternative hypothesis H1, deciding between a one-tailed (p < p0 or p > p0) and a two-tailed (p ≠ p0) test from the wording, the test statistic X ~ B(n, p0) under H0, and what the significance level means.

Why it works

Reasoning from surprise

A hypothesis test uses the result of one sample to decide between two competing claims about a population parameter — here a population proportion pp (the probability of "success": a defective item, a red bead, a late customer). We can't see the whole population, so we reason from how surprising the sample would be if a particular value of pp were true.

The two hypotheses

The null hypothesis H0H_0 is the "no change / status quo" claim, and is always an equality: H0:p=p0H_0 : p = p_0. The alternative H1H_1 is what you are testing for, and its form is chosen from the wording:

H1:p>p0∣H1:p<p0∣H1:p≠p0H_1: p > p_0 \quad\big|\quad H_1: p < p_0 \quad\big|\quad H_1: p \ne p_0

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