Section 2.5: Measures of Variation

1. Explain, in plain English, what variation means in the context of a data set.
2. Define the range of a data set.
3. Explain why the average of the deviations of data points from their average does not give a satisfactory measure of variation.
4. Explain, in words, how to compute the standard deviation from a data set.
5. Specify the units of standard deviation, given the units of a data set.
6. Use the range rule of thumb to make approximate conversions from ranges to standard deviations and vice versa.
7. Use the standard deviation rule of thumb to determine whether a sample value is unusual given a data set’s mean and standard deviation.
8. Given the mean and standard deviation from a data set with a bell-shaped distribution, estimate the proportion of sample values that fall within 1, 2, and 3 standard deviations from the mean.
9. Compute the standard deviation of a data set using Minitab.