STAT 530, Fall 2018
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Homework 2
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For this HW, all problems are mandatory for graduate students and undergraduate students.
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NOTE:  The air pollution data set (from chapter 2) is given on the course web page.
You should use the FULL data set for the problems given below.
You can read the data into R (as a data frame) with the code:

airpol.full <- read.table("http://people.stat.sc.edu/hitchcock/airpoll.txt", header=T)
city.names <- as.character(airpol.full[,1])
airpol.data <- airpol.full[,2:8]


NOTE: For EACH of these problems, also write several sentences 
explaining in words what substantive conclusions about the data
that you can draw from the plots.

1. Do a star plot to display all 7 variables. And also do a plot using Chernoff Faces.  
Write a short paragraph explaining what the plots tell you about the cities.
You can include the "labels" argument to label the drawings for both the stars function and the faces function, e.g.:
labels=city.names  
within the call of each function.

2. Produce a scatterplot matrix for this air pollution data set.  Write a short 
paragraph explaining the main conclusions from the scatterplot matrix.

3.  Produce chiplots for A FEW pairs of variables in the air pollution data set, and write comments about those.  
This exercise is just to give you practice in making and interpreting chiplots.

4.  Do a bivariate boxplot of the pair of variables "Education" and "Mortality" 
from the air pollution data set.  Explain what the plot tells you about the relationship 
between the two variables.  Do you see any outliers?  If so, which cities are they?

5.  Do a bubble plot with "Education" and "Mortality" on the axes and "Population Density" 
represented by the bubbles.  Explain what the plot tells you about the relationships 
among the three variables.  Comment on any notable cities.

NOTE: The preferred way to turn in the homework is to put your answers neatly in a Word document or pdf file and 
upload it in Blackboard according to the instructions.  Alternatively, if you are on campus, 
you could hand in a hard copy to my office (LeConte 209A).