Exam 10: Two-Sample Tests

If you wish to determine whether there is evidence that the proportion of items of interest is Higher in group 1 than in group 2, the appropriate test to use is

In testing for the differences between the means of 2 independent populations where the variances In each population are unknown but assumed equal, the degrees of freedom are

SCENARIO 10-8 A few years ago, Pepsi invited consumers to take the "Pepsi Challenge." Consumers were asked to decide which of two sodas, Coke or Pepsi, they preferred in a blind taste test.Pepsi was interested in determining what factors played a role in people's taste preferences.One of the factors studied was the gender of the consumer.Below are the results of analyses comparing the taste preferences of men and women with the proportions depicting preference for Pepsi. -Referring to Scenario 10-8, suppose Pepsi wanted to test to determine if the males preferred Pepsi more than the females.Using the test statistic given, compute the appropriate p-value for The test.

True or False: Repeated measurements from the same individuals is an example of data collected from two related populations.

SCENARIO 10-6 To investigate the efficacy of a diet, a random sample of 16 male patients is selected from a population of adult males using the diet.The weight of each individual in the sample is taken at the start of the diet and at a medical follow-up 4 weeks later.Assuming that the population of differences in weight before versus after the diet follow a normal distribution, the t-test for related samples can be used to determine if there was a significant decrease in the mean weight during this period.Suppose the mean decrease in weights over all 16 subjects in the study is 3.0 pounds with the standard deviation of differences computed as 6.0 pounds. -Referring to Scenario 10-6, what is the 99% confidence interval estimate for the mean difference in weight before and after the diet?

True or False: The sample size in each independent sample must be the same if we are to test for differences between the means of two independent populations.

The Wall Street Journal recently ran an article indicating differences in perception of sexual Harassment on the job between men and women.The article claimed that women perceived the Problem to be much more prevalent than did men.One question asked to both men and women Was: "Do you think sexual harassment is a major problem in the American workplace?" Some 24% of the men compared to 62% of the women responded "Yes." Suppose that 150 women and 200 men were interviewed.What is the value of the test statistic?

SCENARIO 10-5 10-16 Two-Sample Tests -Referring to Scenario 10-5, the number of degrees of freedom is

SCENARIO 10-5 10-16 Two-Sample Tests -Referring to Scenario 10-5, the value of the sample mean difference is _______ if the difference Scores reflect the results of the exam after the course minus the results of the exam before the Course.

True or False: A statistics professor wanted to test whether the grades on a statistics test were the same for upper and lower classmen.The professor took a random sample of size 10 from each, conducted a test and found out that the variances were equal.For this situation, the professor should use a t test with related samples.

A powerful women's group has claimed that men and women differ in attitudes about sexual Discrimination.A group of 50 men (group 1)and 40 women (group 2)were asked if they thought Sexual discrimination is a problem in the United States.Of those sampled, 11 of the men and 19 Of the women did believe that sexual discrimination is a problem.Assuming W designates Women's responses and M designates men's, which of the following are the appropriate null and Alternative hypotheses to test the group's claim?

SCENARIO 10-4 Two samples each of size 25 are taken from independent populations assumed to be normally distributed with equal variances.The first sample has a mean of 35.5 and standard deviation of 3.0 while the second sample has a mean of 33.0 and standard deviation of 4.0. -