Data Analysis with Microsoft Excel: Updated for Office 2007

Chapter 10 Analysis of Variance 405

Comparing Means with a Boxplot

Earlier you used multiple histograms to compare the distribution of hotel prices

among the different cities. The boxplot is also very useful for this task because

it shows the broad outline of the distributions and displays the medians for

the four cities. Recall that if the data are very badly skewed, the mean might be

strongly affected by outlying values. The median would not have this problem.

To create a boxplot of price versus city:

1 Click Single Variable Charts from the StatPlus menu and then click

Boxplots.

2 Click the Data Values button, and select Price from the list of range

names. Click OK.

3 Click the Categories button, and select City from the range names

list. Click OK.

4 Click the Output button, and direct the output to a new chart sheet

named Boxplots. Click OK.

5 Click OK. The resulting boxplots are shown in Figure 10-10.

Figure 10-10
Boxplot of
room prices
for each city

Compare the medians, indicated by the middle horizontal line (not dotted)

in each box. The median for San Francisco is above the median for Chicago

even though you discovered from the pairwise mean difference matrix that