1. Chapter 9: Hypothesis Tests for One Population Mean 9.1 The Nature of Hypothesis Testing

2. Hypothesis Test Hypothesis: statement that something is true Hypothesis test involves two hypotheses: – Null hypothesis Hypothesis to be tested H 0 – Alternative hypothesis Considered as an alternative to the null H a

3. Hypothesis Tests The problem in a hypothesis test is to decide whether the null hypothesis should be rejected in favor of the alternative hypothesis The null hypothesis for a test concerning a population mean, always specifies a single value for that parameter Notation:

4. Alternative Hypothesis If population mean is different from a specified value (two-tailed): If population mean is less than a specified value (left-tailed): If population mean is greater than a specified value (right-tailed):

5. Example 9.2 The R.R. Bowker Company of New York collects information on the retail prices of books and publishes the data in Publishers Weekly. In 1997, the mean retail price of history books was $43.50. Suppose that we want to perform a hypothesis test to decide whether this year’s mean retail price of history books has increased from the 1997 mean. Determine the null hypothesis: Determine the alternative hypothesis: Classify the hypothesis test as two-tailed, left-tailed, or right-tailed:

6. Example 9.3 Calcium is the most abundant mineral in the body and also one of the most important. It works with phosphorus to build and maintain bones and teeth. According to the Food and Nutrition Board of the National Academy of Sciences, the recommended daily allowance of calcium for adults is 800 mg. Suppose that we want to perform a hypothesis test to decide whether the average person with an income below the poverty level gets less than the RDA of 800 mg. Determine the null hypothesis: Determine the alternative hypothesis: Classify the hypothesis test as two-tailed, left-tailed, or right- tailed:

7. Basic Logic of Hypothesis Testing Take a random sample from the population. If the sample data are consistent with the null hypothesis, do not reject the null. If the sample data are inconsistent with the null hypothesis, reject the null and conclude that the alternative hypothesis is true.

8. Homework P. 390 1 – 10