After reading this chapter, you should be able to:

1. Compute and interpret a range, interquartile range, and semi-interquartile range.
2. Compute and interpret the variance and standard deviation for a population and sample of data using the definitional formula.
3. Compute and interpret the variance and standard deviation for a population and sample of data using the computational formula.
4. Explain why the sample variance and population variance are computed differently.
5. State the characteristics of the standard deviation and explain the empirical rule.
6. Compute the range, variance, and standard deviation using SPSS.