ABSTRACT
In this chapter you will:
Learn how to summarize a sample (a particular set of scores) with a single number or statistic, the arithmetic mean.
Learn what it means to say that the mean is the best fit, in a least-squares sense, to the scores in the sample.
Learn how to describe the variability in a sample and in a population using the variance and the standard deviation.
Learn how to compare scores from different samples or populations using standard scores (Z scores).
Learn how to identify scores so extreme that they might possibly be measuring or copying mistakes.
If you never wanted to generalize beyond a sample, inferential statistical techniques like hypothesis testing would be unnecessary. But very likely you would still want to describe what your sample was like. Basic descriptive statistical techniques, like those described in this chapter, allow you to do exactly that.