Introduction

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Do you have a favorite color of candy-coated chocolate pieces? When you grab a handful, do you have to eat them in a certain color order? If so, you have probably noticed that different samples of the same size have different color distributions. Whenever you take only a sample from your population of interest, you can't be sure what you will get!

In Chapter 1, we described statistics as the process of collecting, describing, and drawing conclusions about data. Thus far, we have primarily investigated collecting and describing data. For the remainder of this course, we will be concerned with drawing conclusions using data. What kinds of conclusions will we draw? Can we be fairly sure that our conclusions are correct? In this chapter we introduce the study of inferential statistics, the process of drawing conclusions about a population based on information obtained from a sample. In doing so, we are generally attempting to answer one of two questions—either “What is the value of the parameter?” or “Is my theory about the parameter true?” We will begin our discussion by considering the first of these questions.