Consider the following data:
These figures provide the depths (in centimeters) at which important archaeological finds were made at four sites in New Mexico (see Woosley and Mcintyre, 1996). Store these data in your R workspace, with one vector containing depth and the other vector containing the site of each observation.
a. Produce side-by-side boxplots of the depths split by group, and use additional points to mark the locations of the sample means.
b. Assuming independence, execute diagnostic checks for normality and equality of variances.
c. Perform and conclude a one-way ANOVA test for evidence of a difference between the means.
In Section 14.4, you looked at the data set providing measurements on petal and sepal sizes for three species of iris flowers. This is available in R as iris.
d. Based on diagnostic checks for normality and equality of variances, decide which of the four outcome measurements (sepal length/width and petal length/width) would be suitable for ANOVA (using the species as the group variable).
e. Carry out one-way ANOVA for any suitable measurement variables.