Prepare answers to the following assignments from the e-text, Applied Statistics in Business and Economics, by Doane and Seward:
Chapter 15 – Chapter Exercises 15.18, 15.22, 15.24, and 15.28
15.18
Sixty-four students in an introductory college economics class were asked how many credits they had earned in college, and how certain they were about their choice of major. Research question: At α = .01, is the degree of certainty independent of credits earned?
Credits Earned Very Uncertain Somewhat Certain Very Certain Row Total
0–9 12 8 3 23
10–59 8 4 10 22
60 or more 1 7 11 19
Col Total 21 19 24 64
H0: The two factors are independent
HA: There is a relationship between the two factors.
Level of Significance: = 1%
Decision Rule: Reject the null hypothesis if p-value < 0.01
Chi-square Contingency Table Test for Independence
Very Uncertain Somewhat Certain Very Certain Total
0-9 Observed 12 8 3 23
Expected 7.55 6.83 8.63 23.00
O - E 4.45 1.17 -5.63 0.00
(O - E)² / E 2.63 0.20 3.67 6.50
Oct-59 Observed 8 4 10 22
Expected 7.22 6.53 8.25 22.00
O - E 0.78 -2.53 1.75 0.00
(O - E)² / E 0.08 0.98 0.37 1.44
60 or more Observed 1 7 11 19
Expected 6.23 5.64 7.13 19.00
O - E -5.23 1.36 3.88 0.00
(O - E)² / E 4.39 0.33 2.11 6.83
Total Observed 21 19 24 64
Expected 21.00 19.00 24.00 64.00
O - E 0.00 0.00 0.00 0.00
(O - E)² / E 7.11 1.51 6.15 14.76
14.76 chi-square
4 df
.0052 p-value
Since the p-value is less than 0.01, the null hypothesis is rejected.
Therefore, there is sufficient evidence to conclude at 5% level of significance that
the degree of certainty is dependent on the credits earned.
15.22
A student team examined parked cars in four different suburban shopping...