For example, if you pack your clothes according to the average temperature for your vacation to Oklahoma City ignoring the ranges, you could end up in a hospital. It’s also important to understand the ranges or standard deviations along with means.
One should always be careful when interpreting results with “average” values, and should understand which average is employed. Even though they can be similar when describing the heights of men, they are usually far off when describing salaries. The book also emphasizes that there are three different numbers one can use when reporting on an “average” value: arithmetic mean, median and mode. Small samples could be very misleading and you should try to find out what the sample size is before making your decision based on the results presented. Obviously, from this result you shouldn’t decide that you would get a head every time you toss a coin. If you toss a penny only 4 times, you could get 4 heads. Another very important factor is the sample size. The method of survey and/or the interviewer also impacts the results. When examining survey results, you should keep in mind that people who complete the surveys are different than those who didn’t respond to the survey and those who respond tend to over or understate the truth. However, a sample with a built-in bias could dramatically change the results. Sampling is critical in statistics because we can’t always count or observe every item in a population and therefore have to base our judgments on a selected sample. The book starts with explaining the importance of sample selection and built-in bias. Some salary figures seem to be outdated but the tricks remain pretty much the same. It’s interesting that although this book was written in 1954, the concepts explained are just as pertinent today. People collecting and presenting the numbers to management could employ some of the tricks explained in this book and therefore, we should be careful when basing our decisions on those numbers.
I think it’s particularly useful for a manager or an executive to read and understand this book, because they are usually presented with a lot of numbers, graphs and charts and are expected to make decisions based on these numbers.
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