Chapter 9: Q3E (page 522)
What is the difference between an observational experiment and a designed experiment?
In a designed experiment, the researcher controls the treatment specifications. While in the observational experiment, he observes the treatments, but he cannot control the treatments.
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Suppose you conduct a 4 * 3 factorial experiment.
a. How many factors are used in the experiment?
b. Can you determine the factor type(s)โqualitative or quantitativeโfrom the information given? Explain.
c. Can you determine the number of levels used for each factor? Explain.
d. Describe a treatment for this experiment and determine the number of treatments used.
e. What problem is caused by using a single replicate of this experiment? How is the problem solved?
Explain the difference between an experiment that employs a completely randomized design and one that employs a randomized block design.
Define an experiment-wise error rate.
Study of mutual fund performance. Mutual funds are classified as large-cap funds, medium-cap funds, or small-cap funds, depending on the capitalization of the companies in the fund. Hawaii Pacific University researchers investigated whether the average performance of a mutual fund is related to capitalization size (American Business Review, January 2002). Independent random samples of 30 mutual funds were selected from each of the three fund groups, and the 90-day rate of return was determined for each fund. The data for the 90 funds were subjected to an analysis of variance, with the results shown in the ANOVA summary table below.
a. State the null and alternative hypotheses for the ANOVA.
Performance of a bus depot. Refer to the International Journal of Engineering Science and Technology (February 2011) study of public bus depot performance, Exercise 9.25 (p. 544). Recall that 150 customers provided overall performance ratings at each of three different bus depots (Depot 1, Depot 2, and Depot 3). The average performance scores were determined to be significantly different at ฮฑ=.05 using an ANOVA F-test. The sample mean performance scores were reported as 
. The researchers employed the Bonferroni method to rank the three performance means using an experiment wise error rate of .05. Adjusted 95% confidence intervals for the differences between each pair of treatment means are shown in the table. Use this information to rank the mean performance scores at the three bus depots.
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