So, we are saying that there is not enough evidence that the population mean is greater than 7. If you fail to reject, then you are saying there is not enough evidence for.
Step 4: Interpret your decision in terms of the problem To make the decision, use the decision rule: Further, the last part of the problem stated “At a significance level of 0.05, does this survey provide evidence to support the firm’s belief?”. Step 3: Compare the p-value to the significance level alpha and make your decisionįrom the last line of the calculator. Enter the values and select the correct tail for the test.Ĥ. Make sure that you highlight Stats and press if your screen looks different from this.ģ. ) Note that if we knew the population standard deviation, we would use a z-test instead.ġ. (We only have the standard deviation from the sample. Make sure you use the form preferred in the class you are taking!) Step 2: Calculate the p-value using your calculator and the correct testĪ t-test is used here since we have a big enough sample, and the population standard deviation is unknown. (*In some books, they use the statement that is the opposite of for the null hypothesis. Putting these together, the null and alternative hypotheses are: The null hypothesis is the equality* statement using the same value: In this case, that is the population mean. In hypothesis testing, we are trying to understand a population value using a sample, so your hypothesis should be in terms of the population parameter. Here, you are testing the firm’s belief that the mean time spent is more than 7 days.
The alternative hypothesis is a statement about what you are testing. At a significance level of 0.05, does this survey provide evidence to support the firm’s belief? Step 1: Write the null and alternative hypotheses They conduct a survey of 32 people who had recently purchased a TV and found that the mean time spent researching the purchase was 7.8 days with a standard deviation of 3.9 days. Suppose that a marketing firm believes that people who are planning to purchase a new TV spend more than 7 days researching their purchase. Example: performing a t-test on the calculator For this example, assume that the requirements for a hypothesis test for the mean are met (randomly selected sample, independent observations, large population size). We will use an example to see how this process works.
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