Database Reference
In-Depth Information
Chapter 5. Proportions and
Percentages
“Baseball is ninety percent mental and the other half is physical.”
—Yogi Berra
Anyone who wants to master the discipline of communicating data needs to learn how to
convey proportions and percentages effectively. We see these types of comparisons every
day, from the quarterly sales reports to the sports page box scores to the side panels of cereal
boxes. Getting them right is important (unless you're Yogi Berra).
Recall from Chapter 4 that proportions are ratios expressed as values from 0 to 1—where the
numerator is a partial amount and the denominator is the total—and percentages are simply
ratios expressed as an amount in each hundred. They are most often used to communicate
three different types of comparisons:
▪ Part-to-whole
▪ Current-to-historical
▪ Actual-to-target
Let's consider each one of these types of comparisons one at a time, starting with part-to-
whole.
Part-to-Whole
Just how much of baseball is physical, and how much is mental? If these two aspects of the
game are mutually exclusive and collectively exhaustive, they should sum to 100%, right?
Yogi's bogus math in this chapter's epigraph is funny because it's different than what we
know to expect.
In honor of Yogi, let's stick with baseball as we consider proportions. In this section, we'll
consider the team batting statistics for the 2012 New York Yankees .
Search WWH ::




Custom Search