110 Excel
EXCEL TIPS
You can also select and format your data labels by clicking the
Data Labels button located in the Labels group of the Chart Lay-
out tab.Creating Bubble Plots
Let’s examine another possible impact on the graduation rate. The data set
also includes the percentage of all freshmen who graduated in the top 25%
of their high school class. We could create a scatter plot of the Graduated
column values versus the Top 25% column values. However it may be more
instructive to include the calculated SAT values in the chart. One way of
observing the relationship among the three variables is through a bubble
plot. A bubble plot is similar to a scatter plot, except that the size of each
point in the plot is proportional to the size of a third value. In this case,
we’ll create a bubble plot of graduation rate versus SAT average, the size
of each plot symbol being determined by the percentage of incoming fresh-
men who graduate in the top 25% of their class. Note that we won’t prove
that this value affects the graduation rate; we are merely exploring whether
there is graphical evidence to suggest such a relationship. Bubble plots are
another chart type supported by Excel and can be easily created using the
Insert tab.To insert a bubble plot:1 Return to the Grad Percents worksheet and select the nonadjacent
cell range D1:E12;K1:K12.
The order of the columns is important in a bubble plot. The values
for the x axis should be listed fi rst, then the values for the y axis, fol-
lowed by the values that determine the size of the plot bubbles.
2 Click the Insert tab and then click the Other Charts button from the
Charts group on the ribbon; then as shown in Figure 3-23, select the
fi rst Bubble chart option from the menu.