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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Define a comparison-wise error rate.
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.
What are the treatments for a designed experiment that uses one qualitative factor with four levelsโA, B, C, and D?
What is the difference between a one-way ANOVA and atwo-way ANOVA?
Robots trained to behave like ants. Robotic researchers investigated whether robots could be trained to behave like ants in an ant colony (Nature, August 2000). Robots were trained and randomly assigned to โcoloniesโ (i.e., groups) consisting of 3, 6, 9, or 12 robots. The robots were assigned the task of foraging for โfoodโ and to recruit another robot when they identified a resource-rich area. One goal of the experiment was to compare the mean energy expended (per robot) of the four different colony sizes.
a. What type of experimental design was employed?
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