July 2025
Beginner
464 pages
9h 31m
English
Content preview from Statistical Analysis with R For Dummies, 2nd Edition
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Chapter 5
Deviating from the Average
IN THIS CHAPTER
Finding out what variation is all about
Working with variance and standard deviation
Exploring R functions that calculate variation
Here’s a well-known statistician joke: Three statisticians go deer hunting with bows and arrows. They spot a deer and take aim. One shoots and the arrow flies off ten feet to the left. The second shoots and the arrow flies ten feet to the right. The third statistician happily yells out, “We got him!”
Moral of the story: Calculating the mean is a helpful way to summarize a set of numbers, but the mean might mislead you. How? By not giving you all the information you typically need. If you rely only on the mean, you might miss important information about the set of numbers.
To avoid missing important information, another type of statistic is necessary — a statistic that measures variation. Think of variation as a kind of average of how much each number in a group of numbers differs from the group mean. Several statistics are available for measuring variation. They all work the same way: The larger the value of the statistic, the more the numbers differ from their mean. The smaller the value, the less ...
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