BUSINESS

BUSINESS

1. Suppose that you measure the time it takes to download a PDF file from the
Internet. Explain why the download time is a continuous numerical variable.
2. What is the difference between a categorical variable and a numerical variable?

3. What is the difference between descriptive and inferential statistics?
4. What is the difference between a sample and a population?
5. What are the assumptions of ANOVA?
6. What are the assumptions of T-test?
7. What are the assumptions of Chi-square?
8. What are the assumptions of Correlation?
9. What are the assumptions of Simple Linear Regression?
10. What are the assumptions of Multiple Regression?
11. The three statistical methods / tests for examining differences are:
T-test, ANOVA (Analysis of Variance) and Chi-square. Please, give the definitions
for each test.
12. The two statistical methods / tests for examining associations are: Correlation and
Regression (Simple and Multiple regression). Please, give the definitions for each test.
13. Form an ordered array, given the following data from a sample of n=8 midterm
exam scores in math:
63, 99, 68, 72, 79, 83, 71, 62
14. Form a stem-and leaf display, given the following data from a sample of n=7
midterm exam scores in physics:
70, 44, 79, 88, 83, 73, 84
15. One of the major measures of the quality of service provided by any organization
is the speed with which the organization responds to customer complaints. A large
family-held department score selling furniture and flooring, including carpet, had
undergone a major expansion in the past several years. In particular, the flooring
department had expanded from 2 installation crews to an installation supervisor, a
measurer, and 15 installation crews. During a recent year, the company got 50
complaints concerning carpet installation. The following data represent the number of
days between the receipt of the complaint and the resolution of the complaint.
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54, 5, 35, 137, 31, 27, 152, 2, 123, 81, 74, 27, 11, 19, 126, 110, 110, 29, 61, 35, 94, 31,
26, 5, 12, 4, 165, 32, 29, 28, 29, 26, 25, 1, 14, 13, 13, 10, 5, 27, 4, 52, 30, 22, 36, 26,
20, 23, 33, 68
a) Construct a frequency distribution and a percentage distribution
b) Form a cumulative percentage distribution
16. The following is a set of data from a sample of n=15
7, 6, 4, 5, 6, 4, 5, 5, 2, 9, 7, 5, 3, 2, 5
a. Compute the mean, median, and mode
b. Compute the range, variance, and standard deviation
c. Are the data skewed? If so, how?
17. What are the differences between a priori probability, empirical probability, and
subjective probability?
18. What is the difference between a simple event and a joint event?
19. What is the difference between mutually exclusive events and collectively
exhaustive events?
20. A researcher is testing the null hypothesis that there is no relationship between
two continuous variables (customers’ satisfaction: continuous dependent variable and
service quality: continuous independent variable). From a sample of n = 16, she
determines that b1 = +4.8 and Sb1 = 1.6.
a) What is the value of tSTAT?
b) What statistical decision should the researcher make? (for 95% confidence
intervals, the t value is -2.145 and +2.145).
c) Construct a 95% confidence interval estimate of the population slope, ß1 (for 95%
confidence intervals, the t value is -2.145 and +2.145).
21. The marketing manager of a large supermarket chain has the business objective of
using shelf space more efficiently. Toward that goal, he would like to use shelf space
to predict the sales of pet food. Data is collected from a random sample of 12 equalsized
stores. For those data, SSR = 20535 and SST = 30025.
a) Determine the coefficient of determination, r2
, and interpret its meaning.
b) Determine the standard error of the estimate.
22. An experiment has a single factor with four groups and eight values in each group.
a) If SSA = 70 and SST = 190, what is SSW?
b) What is MSA?
c) What is MSW?
d) What is the value of FSTAT?
e) At the 0.05 significance level (Fa = 3.89) what is your statistical decision? Please,
give a detailed explanation.
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23. Use the following contingency table:
A B Total
Yes 40 25 65
No 35 45 80
Total 75 70 145
a) Compute the expected frequency for each cell.
b) Compute ?
2
STAT. Is it significant at a = 0.01 (?2
0.01 = 9.2103)? Please, give a
detailed explanation.