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Part I: Vital Statistics about Statistics
(such as delivering babies) because of the ever-increasing malpractice
insurance rates in the state. This is described as a “national epidemic” and
a “health crisis” around the country. Some brief details of the study are
included, and the article states that of the 2,200 Georgia doctors surveyed,
2,800 of them — which they say represents about 18% of those sampled —
were expected to stop providing high-risk procedures.
Wait a minute! That can’t be right. Out of 2,200 doctors, 2,800 don’t perform
the procedures, and that is supposed to represent 18%? That’s impossible!
You can’t have a bigger number on the top of a fraction, and still have the
fraction be under 100%, right? This is one of many examples of errors in
media reporting of statistics. So what’s the real percentage? There’s no way
to tell from the article. Chapter 5 nails down the particulars of calculating
statistics so that you can know what to look for and immediately tell when
something’s not right.
Belaboring the loss of land
In the same Sunday paper was an article about the extent of land development
and speculation across the United States. Knowing how many homes are likely
to be built in your neck of the woods is an important issue to get a handle on.
Statistics are given regarding the number of acres of farmland being lost to
development each year. To further illustrate how much land is being lost, the
area is also listed in terms of football fields. In this particular example, experts
said that the mid-Ohio area is losing 150,000 acres per year, which is 234
square miles, or 115,385 football fields (including end zones). How do people
come up with these numbers, and how accurate are they? And does it help
to visualize land loss in terms of the corresponding number of football fields?
I discuss the accuracy of data collected in more detail in Chapter 16.
Scrutinizing schools
The next topic in the paper was school proficiency — specifically, whether
extra school sessions help students perform better. The article states that
81.3% of students in this particular district who attended extra sessions passed
the writing proficiency test, whereas only 71.7% of those who didn’t participate
in the extra school sessions passed it. But is this enough of a difference to
account for the $386,000 price tag per year? And what’s happening in these ses-
sions to cause an improvement? Are students in these sessions spending more
time just preparing for those exams rather than learning more about writing
in general? And here’s the big question: Were the participants in the extra ses-
sions student volunteers who may be more motivated than the average
student to try to improve their test scores? The article doesn’t say.

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