Chapter 10

Question 1

What must be established to use a two-sample test that compares the
means of samples selected from two populations

Answer 1

You must establish whether the assumption that the variances in the two populations are equal holds.

The statistical method used to test whether the means of each population are different depends on whether the assump-tion holds or not.

Question 2

Define a pooled-variance t test

Answer 2

A pooled-variance t test is used to determine whether there is a significant difference between 2 means

You must assume

• that the random samples are independently selected from two populations and
• that the populations are normally distributed and have equal variances

Question 3

What is the equation for a pooled-variance t test for the difference b/t 2 means

Answer 3

see image

Question 4

Define the variables of a pooled-variance t test

Answer 4

see image

Question 5

Review Regions of Rejection and Nonrejection

Answer 5

see image 3

Question 6

How do you check for normality in each of the two populations of a pooled-variable t test

Answer 6

Use a box-plot

Question 7

What is the equation to determine the confidence interval estimate for the Difference between two Means

Answer 7

see image 4

Question 8

When do you use the separate-variance t test

Answer 8

When

• You can assume that the two independent populations are normally distributed BUT
• You cannot assume that they have equal variances (S²)

Question 9

What are two situations that involve related data

Answer 9

1. When you take repeated measurements from the same item
2. When you match items or individuals according to some characteristic

In either situation, your are interested in the difference between the two related values rather than the individual values themselves

Question 10

What must you assume when you take repeated measurements

Answer 10

You assume the same items or individuals will behave alike if treated alike

Question 11

What is the goal when comparing the means of two related populations

Answer 11

To show that any differences b/t two measurements of the same items or individuals are due to different treatments that have been applied to the items or individuals

Question 12

Review Table for the Differences b/t Individual values for two related populations

Answer 12

see image 5

Question 13

When do you use the Paired t test for the mean difference

Answer 13

If you assume that the different scores are randomly and independently selected from a population that is normally distributed

Question 14

Define the equation for the Paired t test for the mean difference

Answer 14

see image 6

Question 15

Define the confidence interval estimate for the mean difference

w/ equation

Answer 15

To construct a confidence interval estimate for the population mean difference

see image 7

Question 16

Comparing the Proportions for Two Independent Populations

Answer 16

Use the test statistic Z_STAT

Question 17

Define the Z Test for the Difference Between Two Proportions w/ equation

Answer 17

Based on the difference between to sample proportions (p₁ - p₂)

See image 8

Question 18

Define the Confidence Interval Estimate for the Difference Between Two Proportions

Answer 18

see image 9

Question 19

Define the F Test for the Ratio of Two Variances

Answer 19

• Often you need to determine whether two independent populations have the same variability.
• By testing variances, you can detect differences in the variability in two independent popu-lations.

One important reason to test for the difference between the variances of two populations is to determine whether to use

• the pooled-variance t test (which assumes equal variances)
• or the separate-variance t test (which does not assume equal variances) when comparing the means of two independent populations

Question 20

Define the Equation for the F Test Statistic for Testing The Ratio of Two Variances

Answer 20

See image