Spring 2005

# Midterm Exam 3, Monday, Apr. 11

The exam will be worth 100 points (out of 500 for the whole course). Students are responsible for all material covered in lectures since the second midterm and all material in Chapters 3, 19, 20, and 21 of the textbook.

There are some practice problems and answers available. PLEASE, TRY THE PROBLEMS BEFORE YOU LOOK AT THE ANSWERS. Be honest with yourself: Can you answer each question? Could you do it on an exam? I'm concerned by the number of people who did poorly on exam #2, even though it was very similar to (and easier than) the practice problems I had posted beforehand.

Please remember that on the actual exam, a calculator will not be necessary. However, you may use one if you wish.

The following brief outline of topics from the book is not an exhaustive list of things you need to know, but it may help you make sure you have covered the main ideas.

## Chapter 3

Difficulties of constructing measures in statistical experiments

Seven important pitfalls in statistical surveys

Open questions

Closed questions

Clarification of the measurement variables

Measurement of non-numerical items, e.g., emotions, attitudes, self-esteem

Types of variables (categorical vs. quantitative, discrete vs. continuous)

The statistical terms validity, reliability, bias, and variability

## Chapter 19

Random sampling as a tool to perform inference about the population

Difference between population values and sample estimates

The Rule for Sample Proportions

Conditions under which the Rule for Sample Proportions is valid

Applications of the Rule for Sample Proportions

Use of the Rule for Sample Proportions

The Rule for Sample Means

Conditions under which the Rule for Sample Means is valid

Applications of the Rule for Sample Means

Use of the Rule for Sample Means

Relationship between increasing the sample size and the width of a confidence interval

## Chapter 20

Definition and interpretation of a confidence interval

Examples of confidence intervals reported by the media

Standard deviation of all possible sample proportions

Confidence intervals for a population proportion

95% (and other levels of) confidence

Relationship between the margin of error and the level of confidence

## Chapter 21

Calculation of the Standard Error of the Mean (SEM)

Definitions of the population S.D., the sample S.D., and the SEM

Confidence intervals for a population mean

Relationship between the margin of error and the level of confidence

Relationship between the level of confidence, sample size, and width of the confidence interval

Relationship between the multipliers for 95% confidence interval and for other levels of confidence

Standard error of difference of sample means: The square root of [(SEM1)2 + (SEM2)2]

Confidence intervals for the difference between two population means

Confidence intervals for the difference between two population proportions

Interpretation of a confidence interval