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Unformatted text preview: Your next step is to choose a probability level for the test. You know that the sample mean must be lower than 17 per 10,000 in order to reject the null hypothesis, but how much lower? You settle on a probability level of 5 percent. That is, if the mean admission rate for the sample of sunny hospitals is so low that the chance of obtaining that rate from a sample selected at random from the national population is less than 5 percent, you will reject the null hypothesis and conclude that there is evidence to support the hypothesis that exposure to the sun reduces the incidence of depression. Next, you look up the critical z-scorethe z-score that corresponds to your chosen level of probabilityin the standard normal table. It is important to remember which end of the distribution you are concerned with. Table 2 in "Statistics Tables" lists the probability the distribution you are concerned with....
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- Fall '08