Page 45 - Statistics for Dummies

Chapter 2: The Statistics of Everyday Life
about 2,000 telephone calls, 2,500 e-mail messages, and 200 letters per week on
average — would you want to be the one counting all of those?) is, “Can I carry
this on a plane?” This can refer to anything from an animal to a wedding dress to
a giant tin of popcorn. (I wouldn’t recommend the tin of popcorn. You have to
put it in the overhead compartment horizontally, and because things shift during
flight, the cover will likely open; and when you go to claim your tin at the end of
the flight, you and your seatmates will be showered. Yes, I saw it happen once.)
The number of reported responses in this case leads to an interesting statis-
tical question: How many operators are needed at various times of the day
to field those calls, e-mails, and letters coming in? Estimating the number of
anticipated calls is your first step, and being wrong can cost you money (if
you overestimate it) or a lot of bad PR (if you underestimate it). These kinds
of statistical challenges are tackled in Chapter 13.
Surveying sexual stats
In today’s age of info-overkill, it’s very easy to find out what the latest buzz 29
is, including the latest research on people’s sex lives. An article in my paper
reported that married people have 6.9 more sexual encounters per year than
people who have never been married. That’s nice to know, I guess, but how
did someone come up with this number? The article I’m looking at doesn’t
say (maybe some statistics are better left unsaid?).
If someone conducted a survey by calling people on the phone asking for
a few minutes of their time to discuss their sex lives, who will be the most
likely to want to talk about it? And what are they going to say in response to
the question, “How many times a week do you have sex?” Are they going to
report the honest truth, tell you to mind your own business, or exaggerate a
little? Self-reported surveys can be a real source of bias and can lead to mis-
leading statistics. But how would you recommend people go about finding
out more about this very personal subject? Sometimes, research is more dif-
ficult than it seems. (Chapter 16 discusses biases that come up when collect-
ing certain types of survey data.)
Breaking down weather reports
Weather reports provide another mass of statistics, with forecasts of the next
day’s high and low temperatures (how do they decide it’ll be 16 degrees and
not 15 degrees?) along with reports of the day’s UV factor, pollen count, pol-
lution standard index, and water quality and quantity. (How do they get these
numbers — by taking samples? How many samples do they take, and where do
they take them?) You can find out what the weather is right now anywhere in
the world. You can get a forecast looking ahead three days, a week, a month,
or even a year! Meteorologists collect and record tons and tons of data on the
weather each day. Not only do these numbers help you decide whether to take

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