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7.4 Hypothesis Testing for Proportions • Key Concepts: – Sample Proportion vs Population Proportion – Sampling Distribution of the Sample Proportion – The z-test for a Population Proportion p 7.4 Hypothesis Testing for Proportions • We built confidence intervals for a population proportion p in chapter 6. – We used the sampling distribution of sample proportions to build the interval: p p p pq n p is approximately normal provided n p 5 and nq 5 7.4 Hypothesis Testing for Proportions • How can we use this information? – Since we know the sample proportions are normally distributed and we’re assuming the null hypothesis is true, we can standardize p-hat as follows: z p po po 1 po n where po is the hypothesized population proportion 7.4 Hypothesis Testing for Proportions • Since our test statistic follows the standard normal distribution, we can use the p-value or the critical-value approach in these tests. – Guidelines are given on page 388. #12 p. 391 (Asthma) #16 p. 392 (Cat Ownership)