Reasoning Skills and Statistics Help

Updated on Sep 29, 2011

Introduction to Reasoning Skills and Statistics

"He uses statistics as a drunken man uses lampposts—for support rather than for illumination."

—Andrew Lang, Scottish poet and novelist (1844–1912)

Lesson Summary

Statistics are often used to strengthen arguments—but they aren't always trustworthy. This lesson will show you how to judge the validity of statistics and how to make sure that any statistics you cite are credible.

There's strength in numbers. Whether on the battlefield or in the boardroom, the more people you have fighting for a cause, the more likely you are to win. There's strength in numbers in arguments, too—statistics generally carry more weight and sound more valid than opinions. That's because numbers look concrete, factual, and objective. But numbers are not always to be trusted. Like words, numbers can be—and often are—manipulated. As a critical thinker, you need to beware of the kinds of tricks numbers can play, and you need to know how to evaluate surveys, statistics, and other figures before you accept them as valid.

Consider the Source

One of your first priorities when you come across a figure or statistic is to consider the source. Where is this information coming from? You need to know the source so you can consider its credibility.

Figures are often cited without naming their source. This should automatically raise a red flag. When there's no source acknowledged, that figure could come from anywhere. Here's an example:

Eighty percent of all Americans believe that there is too much violence on television.

Our immediate reaction might be to say "Wow! Eighty percent! That's an impressive statistic." But because this claim does not indicate a source, you have to fight your instinct to accept the number as true. The question, "Who conducted this survey?" must be answered in order for you to be able to assess the validity of the figure. A figure that isn't backed by a credible source isn't worth much and can't be accepted with confidence. Unfortunately, you have to consider that the claimant could have made it up to give the appearance of statistical support for his argument.

If the claimant does provide a source, then the next step is to consider the credibility of that source. Remember, to determine credibility, look for evidence of bias and level of expertise.

Here's that statistic again attributed to two different sources:

  1. According to Parents Against Television Violence (PATV), 80 percent of Americans believe that there is too much violence on TV.
  2. According to a recent University of Minnesota survey, 80 percent of Americans believe there is too much violence on TV.

Would you accept the statistic as offered by source number 1? How about by source number 2?

While both sources may have a respectable level of expertise, it should be acknowledged that the people who conducted the university study probably have a higher level of expertise. More importantly, the source in number 1—Parents Against Television Violence—should encourage you to consider their statistics with caution. Is a group such as PATV likely to be biased in the issue of television violence? Absolutely. Is it possible, then, that such an organization could offer false or misleading statistics to support its cause? Yes. Would it be wise, therefore, to accept this statistic only with some reservations? Yes.

The university's study, however, is much more likely to have been conducted professionally and accurately. Scholarly research is subject to rigorous scrutiny by the academic community, so the university's findings are probably quite accurate and acceptable. There's less reason to suspect bias or sloppy statistical methods.

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