# Week3: BoxPlotting

+/- all
Objective: learn to construct and interpret Box-and-Whisker Plots

## A. What is a box-and-whisker plot?

brief: A box-and-whisker plot (or just “boxplot”) is a graphical display that can be used to determine features of a quantitative variable (such as the center, spread, and even shape).

View the following ActivStats spplets to learn how to construct and interpret box-and-whisker plots:

Let’s go through the construction and interpretation of the box-and-whisker plot in more detail with another example.

## B. How to construct a box-and-whisker plot by hand.

( show me the steps ... )

## C. Interpreting a box-and-whisker plot

1. The center and spread of the data can be determined from the box-and-whisker plot.

3. Even some features of the shape can be determined from the box-and-whisker plot.

4. (Show shape)

## D. Using box-and-whisker plots to compare the distribution of a quantitative variable between two or more groups.

When two (or more) box-and-whisker plots are displayed next to each other on the same graph using a common scale on the axis (one for each of the groups being compared), they are called side-by-side box-and-whisker plots. Such plots are very useful for comparing the quantitative variable of interest between two (or more) groups. View the following ActivStats applet to learn more about using side-by-side box-and-whisker plots to compare the distribution of a quantitative variable between groups.