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### 15.1. Common Statistical Terminology

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If you are not an avid statistician you are going to quickly notice that statistical functions use a lot of different terminology. By understanding some of the terms outlined in this section, you should be able to quickly determine which statistical functions you need to use to produce the desired results.

*Mean*Indicates the arithmetic average of a set of numbers. This is an attempt to find the center of a distribution.

*Median*Indicates a point on a scale of measures where half of the observations are less than or equal to the median, and half are greater.

*Population*Specifies a well-defined collection of all the observations in which we are interested, for example, the total number of seniors graduating in Spring 2000.

*Range*Indicates the distance between the largest and smallest value.

*Sample*Specifies a subset of a population. For example, if a population were the senior class of 2000, a subset would be the seniors who are receiving college scholarships.

*Variance*Characterizes the dispersion within a population. The variance is essentially the mean squared deviation of a dataset, where the deviation is the distance between each observation and the mean.