Chapter 2: Graphs, Charts, and Tables--Describing Your Data

52 CHAPTER 2 • GRAPHS, CHARTS, AND TABLES—DESCRIBING YOUR DATA
FIGURE 2.8
Excel 2007 Output of
the Joint Relative
Frequencies
Excel 2007 Instructions:
1. Place cursor in the Gender
numbers of the PivotTable.
2. Right-click and select
Value Field Settings.
3. On the Show values as
tab, click on the down
arrow and select % of
total.
4. Click OK. In Figure 2.8 we have used the
Data Field Settings of the Excel
PivotTable to represent the data as
percentages.
total 300 people in the survey. For example, the $540-to-$689 class had 20.33% (61) of the
300 customers. The male customers with balances in the $540-to-$689 range constituted
15% (45) of the 300 customers, whereas females with that balance level made up 5.33%
(16) of all 300 customers. On the surface, this result seems to indicate a big difference
between males and females at this credit balance level.
Suppose we really wanted to focus on the male-versus-female issue and control for
the fact that there are far more male customers than female. We could compute the percentages
differently. Rather than using a base of 300 (the entire sample size), we might
instead be interested in the percentages of the males who have balances at each level, and
the same measure for females. 2 Figure 2.9 shows the relative frequencies converted to
FIGURE 2.9
Minitab Relative
Frequency
Distribution—Males
and Females
Minitab Instructions:
1. Open file: Capital.MTW.
2. Steps 2–7 as in Figure 2.7.
3. Click on Stat > Tables >
Cross Tabulation and
Chi-square.
4. Under Categorical
variables For rows enter
Classes column and For
columns enter Gender
column.
5. Under Display, check
Total Percents.
6. Click OK.
2 Such distributions are known as marginal distributions.