Robotic researchers investigated whether robots could be trained to behave like ants in an ant colony (Nature, Aug. 2000). Robots were trained and randomly assigned to "colonies" (i.e., groups) consisting of 3, 6, 9, or 12 robots. The robots were assigned the task of foraging for "food" 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?
b. Identify the treatments and the dependent variable.
c. Set up the null and alternative hypotheses of the test.
d. The following ANOVA results were reported: F = 7.70, numerator df = 3, denominator df = 56, p-value e. Multiple comparisons of mean energy expended for the four colony sizes were conducted using an experiment-wise error rate of .05. The results are summarized below.

How many pair wise comparisons are conducted in this analysis?
f. Refer to part e. Interpret the results shown in the table.

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Sample mean: Group size: 97 93 .80 12 95