solution

Carl Sagan’s intelligence data. In his book, The Dragons of Eden, Carl Sagan presented a graph showing the brain and body masses, both on log scale, of a collection of animal species. The purpose of the graph was to describe an intelligence scale: the ratio of the average brain weight over the average body weight to the power of 2/3.

(a) Read the data (in file Intelligence.csv) into R and graph brain weight against body weight, both in logarithmic scales. The brain weight is in grams and body weight is in kilograms. Can you tell which species has the highest intelligence from this figure?

(b) Calculate the intelligence measure (call it Int) and add the result as a new column to the data frame.

(c) Use the function dotplot from package lattice to plot the intelligence measure directly: dotplot (Species~Int, data=Intelligence)

(d) The dot plot orders the species alphabetically. Reorder the column based on the intelligence scale using function ordered and redraw the dot plot so that the species are sorted based on their intelligence scales. Is there a problem in the data? If so, what might be the cause of the problem?