Name: __________________________________
Chapter Exercises
Chapter 9: Testing Means: The independent-samples t Test
1. An investigator thinks that people under the age of forty have vocabularies that are different than those of people over sixty years of age. The investigator administers a vocabulary test to a group of 31 younger subjects and to a group of 31 older subjects. Higher scores reflect better performance. The mean score for younger subjects was 14.0 and a sum of squares of 400. The mean score for older subjects was 20.0 and a sum of squares of 300. Does this experiment provide evidence for the investigator’s theory?
As part of your answer:
Please provide the null and alternative hypotheses.
H0:
H1:
Using an alpha level of .05, what is the critical point for this 2-tailed test?
Using an alpha level of .05, test the null hypothesis using an independent-samples t-test. Show your work.
State your conclusion regarding the results from this test. Do we reject or fail to reject the null? Why?
2. An investigator predicts that dog owners in the country spend a different amount of time walking their dogs than do dog owners in the city. The investigator gets a sample of 39 city owners and 43 country owners. The mean number of hours per week that city owners spend walking their dogs is 10.0 and a sum of squares of 100. The mean number of hours country owners spent walking their dogs per week was 15.0 and a sum of squares of 110. Is there a difference in the amount of time that city and country dog owners spend walking their dogs?
As part of your answer…
Please provide the null and alternative hypotheses.
H0:
H1:
Using an alpha level of .05, what is the critical point for this 2-tailed test?
Using an alpha level of .05, test the null hypothesis using an independent-samples t-test. Show your work.
State your conclusion regarding the results from this test. Do we reject or fail to reject the null? Why?
3. An investigator theorizes that people who participate in a regular program of exercise will have levels of systolic blood pressure that are significantly different from that of people who do not participate in a regular program of exercise. To test this idea the investigator randomly assigns 21 subjects to an exercise program for 10 weeks and 21 subjects to a non-exercise comparison group. After ten weeks the mean systolic blood pressure of subjects in the exercise group is 137 and a sum of squares of 2100. After ten weeks, the mean systolic blood pressure of subjects in the non-exercise group is 127 and a sum of squares of 1701. Please test the investigator’s theory using an alpha level of .05.
As part of your answer please…
Please provide the null and alternative hypotheses.
H0:
H1:
Using an alpha level of .05, what is the critical point for this 2-tailed test?
Using an alpha level of .05, test the null hypothesis using an independent-samples t-test. Show your work.
State your conclusion regarding the results from this test. Do we reject or fail to reject the null? Why?
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