# Study

### Chapter Summary

There are two major approaches to describing how dispersed a variable is. One approach is to give ranges connected to specific points of the distribution. To find these key points, we need only add a cumulative percent column to our frequency. The other approach looks at how far each case is from the mean by calculating the standard deviation. In calculating the standard deviation, we set up our work table differently depending on whether we are working with raw or tabular data.

### Learning Objectives

After reading this chapter, you should:

• Be able to calculate the range of a distribution
• Be able to find the 5 point summary of a distribution
• Know how to interpret the interquartile range
• Be able to calculate the standard deviation from raw data
• Be able to calculate the standard deviation from tabular data
• Be able to calculate the standard deviation for a dichotomous variable
• Know how to get measures of dispersion in SPSS
• Be able to collapse variables in SPSS