Assignment 5 – Week 7 – Due February 21st at 11:59 Instructor: Dr. Charles Edeki
Submit the assignment in the Assignment 5 drop box. Total points is 50 (Each question is 10 points).
Note: You can solve the questions manually or use Excel or SPSS to solve the questions.
Student Name: Date:
A study by a bank compared the average savings of customers who were depositors for three years or less with
those who had been depositors for more than three years. The results of a sample are:
To test that the two groups of customers have equal savings rates, what is the p-value for a two-tailed test?
A financial planner wants to compare the yield of income and growth mutual funds. Fifty thousand
dollars is invested in each of a sample of 35 income and 40 growth funds. The mean increase for a
two-year period for the income funds is $900. For the growth funds, the mean increase is $875.
Income funds have a sample standard deviation of $35; growth funds have a sample standard
deviation of $45. Assume that the population standard deviations are equal.
At the 0.05 significance level, is there a difference in the mean yields of the two funds?
What is the computed value of the test statistic?
Identify the design of each experiment below as paired samples or independent samples. In each case
give the df.
a. Ten students compared the legibility of headlines. In one condition the headlines were all in CAPITALS. In the other condition the first letters were capitalized. Each student
judged on a scale of 1-10. Five judged the all capitals headline; five judged the first letter
only capitalized. b. On the basis of Critical Reading SAT scores, each male was matched with a female. Then
the math SAT scores were found and the mean for the 18 males was compared to the mean
of the 18 females. c. To control for socioeconomic status, this study used only families with annual incomes in
the $40-50,000 a year range. Thirty-six fathers of one-year-olds were compared. Half had
participated in the Lamaze method a year earlier when their child was born and half had not.
A non-verbal behavior score was taken during a 10-minute father-child session. d. d. A comparison of 54 fathers to their 54 sons all of whom were union members, showed
the older men had higher spatial ability scores.
A social psychologist wanted to determine whether attitudes of men toward abortion were different in
rural and urban areas. He prepared a questionnaire and administered it to a group of city dwellers and
a group of country dwellers. Each city man was matched with a country man on age, income, and
education. High scores indicate positive attitudes toward abortion. Here are the questionnaire scores.
Rural Men Urban Men
a. What statistical method should be used and why?
b. Calculate a 95% confidence interval about the difference in the two populations.
c. Use the CI to test the null hypothesis that rural and urban men have identical attitudes toward abortion.
Here is an experiment modeled after that of Triplett (1897), who conducted the first social psychology experiment.
Twenty-four 5th graders were given fishing reels. Twelve were tested individually. The number of
yards of line reeled in 10 seconds was recorded for each. The other group was tested together
under conditions of competition; the one who reeled the most line got to keep the reel. The
following summary statistics were obtained.
Individuals Group Competition
2 3347 7308
N 12 12
Analyze the results using a 99 percent confidence interval and d. Write a conclusion.