Manipulating Statistics Study Guide (page 3)

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Updated on Sep 19, 2011


Statistics is simply a mathematical science that gathers information about a population so that population may be described usefully. Statistics are often used to draw conclusions and make decisions based on that information. So, what's the problem?

Statistics are complicated and their problems can be numerous. In general, though, problems with statistics are similar to those of other types of numerical data; namely, they can be gathered, analyzed, and/or interpreted incorrectly, or mishandled by someone with a bias. Let's look at two common problems with statistics.

  • Is it meaningful? Many parents worry when they hear that the average baby walks at 13 months. They may conclude that something must be wrong with their 18-month-old who is still crawling. But, studies have proven that at age two, there are no developmental differences between early walkers and babies who walk later. So the statistic is not meaningful; there is nothing abnormal about an 18-month-old who still crawls. Here is another example. When national standardized test scores were analyzed, it was concluded that since students from wealthy communities had higher scores, they were smarter than students in poorer communities. Is that a meaningful, accurate conclusion? Probably not; it doesn't take into account the many other variables that can explain lower test scores, such as teacher quality, less test preparation, fatigue, and even breakfast on the day of testing.


Always check the source of data. Is the source credible? Look for another source that gives similar data to strengthen the credibility.


Never trust numbers alone to prove a point. Ask yourself, "Why should I believe these statistics?" Always look for some other kind of evidence or an example to reinforce the figures.

In Short

It is just as easy to deceive with numbers as it is with words. Surveys, studies, and statistics are conducted and interpreted by researchers who might have a bias, or simply lack the skills necessary to do their jobs properly. Therefore, it is important to evaluate numbers before accepting them as truth. Ask questions about how the information was gathered, what its margin of error is, and how meaningful it is. Does the conclusion make sense, or does it seem to distort the findings? Thinking critically about the many numbers you encounter will help you to rely only on information that is objective and accurate.

Skill Building Until Next Time

  • Watch a news broadcast and listen for the results of a survey or poll. Does the newscaster tell the margin of error? Why is it important to know this number?
  • Look for a print or article that includes a statistic. Why was it included? Does it seem accurate and objective? How else could the advertiser or writer have made the point without using numbers?

Exercises for this concept can be found at Manipulating Statistics Practice Exercises.

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