HOW TO LIE WITH STATISTICS by Darrell Huff, Irving Geis

• The secret language of statistics, so appealing in a fact-minded culture, is employed to sensationalize, inflate, confuse, and oversimplify.
• The crooks already know these tricks; honest men must learn them in self-defense.
• The test of the random sample is this: Does every name or thing in the whole group have an equal chance to be in the sample?
• When you are told that something is an average you still don’t know very much about it unless you can find out which of the common kinds of average it is—mean, median, or mode.
• With a large group any difference produced by chance is likely to be a small one and unworthy of big type.
• Only when there is a substantial number of trials involved is the law of averages a useful description or prediction.
• Often an average—whether mean or median, specified or unspecified—is such an oversimplification that it is worse than useless.
• How accurately your sample can be taken to represent the whole field is a measure that can be represented in figures: the probable error and the standard error.
• When numbers in tabular form are taboo and words will not do the work well, as is often the case, there is one answer left: Draw a picture.
• About the simplest kind of statistical picture, or graph, is the line variety. It is very useful for showing trends, something practically everybody is interested in showing or knowing about or spotting or deploring or forecasting.
• IF YOU can’t prove what you want to prove, demonstrate something else and pretend that they are the same thing.
• You can use accident statistics to scare yourself to death in connection with any kind of transportation…if you fail to note how poorly attached the figures are.
• There are many other forms of counting up something and then reporting it as something else. The general method is to pick two things that sound the same but are not.
• Many statistics, including medical ones that are pretty important to everybody, are distorted by inconsistent reporting at the source.
• To avoid falling for the post hoc fallacy and thus wind up believing many things that are not so, you need to put any statement of relationship through a sharp inspection.
• Another thing to watch out for is a conclusion in which a correlation has been inferred to continue beyond the data with which it has been demonstrated.
• A correlation of course shows a tendency that is not often the ideal relationship described as one-to-one.
• A negative correlation is simply a statement that as one variable increases the other tends to decrease.
• Permitting statistical treatment and the hypnotic presence of numbers and decimal points to befog causal relationships is little better than superstition.
• MISINFORMING people by the use of statistical material might be called statistical manipulation; in a word (though not a very good one), statisticulation.
• Percentages offer a fertile field for confusion. And like the ever-impressive decimal they can lend an aura of precision to the inexact.
• Any percentage figure based on a small number of cases is likely to be misleading. It is more informative to give the figure itself. And when the percentage is carried out to decimal places you begin to run the scale from the silly to the fraudulent.
• It is sometimes a substantial service simply to point out that a subject in controversy is not as open-and-shut as it has been made to seem.
• Look for conscious bias.
• Look sharply for unconscious bias.
• Many figures lose meaning because a comparison is missing.
• one of them had married a faculty man.
• Strange things crop out when figures are based on what people say—even about things that seem to be objective facts.
• “Does it make sense?” will often cut a statistic down to size when the whole rigmarole is based on an unproved assumption.
• Many a statistic is false on its face. It gets by only because the magic of numbers brings about a suspension of common sense.
• Extrapolations are useful, particularly in that form of soothsaying called forecasting trends. But in looking at the figures or the charts made from them, it is necessary to remember one thing constantly: The trend-to-now may be a fact, but the future trend represents no more than an educated guess.