Question 1: A researcher hypothesizes that individuals who listen to classical music will score differently from the general population on a test of spatial ability. On a standardized test of spatial ability, µ =58. A random sample of 14 individuals who listen to classical music is given the same test.
Their scores on the test are 52, 59, 63, 65, 58, 55, 62, 63, 53, 59, 57, 61, 60, 59.
a. Is this a one- or two-tailed test?
b. What are H0 and Ha for this study?
c. Compute tobt.
d. What is tcv?
e. Should H0 be rejected? What should the researcher conclude?
f. Determine the 95% confidence interval for the population mean, based on the sample mean.
Question 2: A researcher believes that the percentage of people who exercise in California is greater than the national exercise rate. The national rate is 20%. The researcher gathers a random sample of 120 individuals who live in California and finds that the number who exercise regularly is 31 out of 120.
a. What is obt?
b. What is df for this test?
c. What is cv?
d. What conclusion should be drawn from these results?
Question 3: Researchers at a food company are interested in how a new spaghetti sauce made from green tomatoes (and green in color) will compare to their traditional red spaghetti sauce. They are worried that the green color will adversely affect the tastiness scores. They randomly assign subjects to either the green or red sauce condition. Participants indicate the tastiness of the sauce on a 10-point scale. Tastiness scores tend to be skewed. The scores follow.
Participant Red Sauce Green Sauce
1 7 4
2 6 3
3 9 6
4 10 8
5 6 7
6 7 5
7 8 9
a. What statistical test should be used to analyze these data?
b. Identify H0 and Ha for this study.
c. Conduct the appropriate analysis.
d. Should H0 be rejected? What should the researcher conclude?
Question 4: You notice in your introductory psychology class that more women tend to sit up front, and more men sit in the back. To determine whether this difference is significant, you collect data on the seating preferences for the students in your class. The data follow.
Men Women
Front of the Room 15 27
Back of the Room 32 19
a. What is X2 obt?
b. What is df for this test?
c. What is X2cv?
d. What conclusion should be drawn from these results?