4.2. Measures of Variation
A second important property that describes a set of numerical data is variation. Variation is the amount of dispersion, or spread, in a set of data, be it a sample or a population. Three frequently used measures of variation are the range, the variance, and the standard deviation.
The range is the simplest measure of variation in a set of data.
The range is equal to the largest value minus the smallest value:
Using the data pertaining to the time to get ready in the morning on page 43:
Range = largest value – smallest value
Range = 52 – 29 = 23 minutes
This means that the largest difference between any two days in the time to get ready in the morning ...