CHAPTER 11

Confidence Intervals and Introduction to Inference

IN THIS CHAPTER

Summary: In this chapter we begin our formal study of inference by introducing the t distribution (as an
adjustment to z ) and talk about estimating a population parameter. We will learn about confidence
intervals, a way of identifying a range of values that we think might contain our parameter of interest. We
will develop intervals to estimate a single population mean, a single population proportion, the difference
between two population means, and the difference between two population proportions. We will also be
introduced to the logic behind significance testing as well as to the types of errors you have to worry
about when testing. There’s a lot in this chapter, and you need to internalize most of it.

Key Ideas

Estimation

Confidence  Intervals

t Procedures

Choosing    a   Sample  Size    for a   Confidence  Interval

P   -Value

Statistical Significance

Hypothesis-Testing  Procedure

Errors  in  Hypothesis  Testing

The Power   of  a   Test

Estimation and Confidence Intervals

As we proceed in statistics, our interest turns to estimating unknown population values. We have