Page 50 - Statistics for Dummies

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Part I: Vital Statistics about Statistics
Detecting Errors, Exaggerations,
and Just Plain Lies
Statistics can go wrong for many different reasons. First, a simple, honest
error can occur. This can happen to anyone, right? Other times, the error is
something other than a simple, honest mistake. In the heat of the moment,
because someone feels strongly about a cause and because the numbers
don’t quite bear out the point that the researcher wants to make, statistics
get tweaked, or, more commonly, exaggerated, either in their values or how
they’re represented and discussed.
Another type of error is an error of omission — information that is missing
that would have made a big difference in terms of getting a handle on the real
story behind the numbers. That omission makes the issue of correctness dif-
ficult to address, because you’re lacking information to go on.
You may even encounter situations in which the numbers have been com-
pletely fabricated and can’t be repeated by anyone because they never hap-
pened. This section gives you tips to help you spot errors, exaggerations, and
lies, along with some examples of each type of error that you, as an informa-
tion consumer, may encounter.
Checking the math
The first thing you want to do when you come upon a statistic or the result
of a statistical study is to ask, “Is this number correct?” Don’t assume it is!
You’d probably be surprised at the number of simple arithmetic errors that
occur when statistics are collected, summarized, reported, or interpreted.
To spot arithmetic errors or omissions in statistics:
✓ Check to be sure everything adds up. In other words, do the percents
in the pie chart add up to 100 (or close enough due to rounding)? Do the
number of people in each category add up to the total number surveyed?
✓ Double-check even the most basic calculations.
✓ Always look for a total so you can put the results into proper perspec-
tive. Ignore results based on tiny sample sizes.
✓ Examine whether the projections are reasonable. For example, if three
deaths due to a certain condition are said to happen per minute, that
adds up to over 1.5 million such deaths in a year. Depending on what
condition is being reported, this number may be unreasonable.

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