Introduction to Statistics (MAT/SST 115.03 2008S)

R notes for Activity 8-3: Matching Game


Reading Data

Although the book says that the data are stored in the file Matching, we've separated the data into three separate files: MonopoloyPrices.csv, SnowfallAmounts.csv, and QuizPercentages.csv. All are stored in the standard data directory for this course. Recall that you can read a file into a frame with a command like

MonopolyPrices = read.csv("/home/rebelsky/Stats115/Data/MonopolyPrices.csv")

You should be able to figure out the commands to read the other two data sets.

Dot Plots

We need to load an appropriate library to do dotplots, but otherwise it remains straightforward. Particularly since we do not plan to use these graphs for anything but a quick observation, we don't even need to fool with axis labels.

library(BHH2, lib="/home/rebelsky/Stats115/Packages")
dotPlot(MonopolyPrices, main="Prices of Monopoly Properties")

You might note something a bit strange about this command. Traditionally, we use dotPlot with vectors. And, if you think about it carefully, MonopolyPrices is a data frame, rather than a vector. So, why does the command work? Apparantly, R is smart enough to treat a data frame with one column as a vector, at least for this plot.

If, however, you want to create a histogram, you'll need to extract the column (which is also called MonopolyPrices).

hist(MonopolyPrices$MonopolyPrices)

Here's a fine-enough grained histogram that it replicates the dotplot.

hist(MonopolyPrices$MonopolyPrices, breaks=seq(from=0,to=500,step=25))

Numeric Measures

As you already know, you can get the mean and median separately with mean and median. You can also get them together with a host of other information by using summary.

summary(MonopolyPrices)

Creative Commons License

Samuel A. Rebelsky, rebelsky@grinnell.edu

Copyright (c) 2007-8 Samuel A. Rebelsky.

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