Question 1

The t statistic can only be a positive number.

Accepted Answer

A) True 
 B)False

Question 2

Mary and Joe conduct two separate studies. By an amazing coincidence, they obtain exactly the same sample means and standard deviations. However, Mary's sample is twice as large as Joe's. Which of these is true?

Accepted Answer

A)  Mary's alternative hypothesis will be larger than Joe's. 
B)  The two studies have the same likelihood of supporting their research hypotheses. 
C)  Joe is more likely to reject the null hypothesis than Mary. 
D)  Mary's critical values will be smaller than Joe's.

Question 3

In making the decision to reject the null hypothesis, what would happen if you were to change α from .05 to .01?

Accepted Answer

A)  You would be less likely to reject the null hypothesis. 
B)  Your sample would get smaller. 
C)  The region of rejection would get larger. 
D)  You would be more likely to reject the null hypothesis.

Question 4

The variability of the sampling distribution of the difference is measured by the ______.

Accepted Answer

A)  standard error of the differences 
B)  sample means 
C)  modality of a set of data 
D)  probability of obtaining a particular value of the population mean

Question 5

A study tests the difference between 20 Democrats and 20 Republicans. In this example, the degrees of freedom is equal to ______.

Accepted Answer

A)  18 
B)  19 
C)  38 
D)  39

Question 6

In an introduction to statistics course, the students are given a basic exam to complete in class. Over the next few weeks, the students are given review sessions and then asked to complete the exam. The professor in the course expects the students' grades on the exam to increase. In analyzing the data, how should the alternative hypothesis be stated?

Accepted Answer

A)  µ1 = µ2 
B)  µD ≠ 0 
C)  µ1 > µ2 
D)  µ1 2

Question 7

A researcher calculates the t-test for independent means and reports the following result: t(48) = 2.97, p < .01. This research study consisted of a TOTAL of ______ participants.

Accepted Answer

A)  25 
B)  48 
C)  49 
D)  50

Question 8

A researcher hypothesizes that there is a difference in level of fear of crime for the elderly and young adults. In conducting an analysis to test this hypothesis, how might the alternative hypothesis be stated?

Accepted Answer

A)  H1: μD = 0 
B)  H1: μD ≠ 0 
C)  H1: μElderly ≠ μYoung Adults 
D)  H1: μElderly > μYoung Adults

Question 9

In which of the following situations would you be most likely to set alpha at .10 rather than the traditional .05?

Accepted Answer

A)  Your target population is very small. 
B)  You collect data from a large (rather than small) sample. 
C)  You don't want to reject the null hypothesis. 
D)  You want to use a directional alternative hypothesis.

Question 10

A researcher states the following hypotheses: H0: μDogs = μCats and H1: μDogs ≠ μ Cats. Assuming she collects data from 9 dogs and 9 cats, what is the appropriate critical value?

Accepted Answer

A)  1.734 
B)  2.120 
C)  2.110 
D)  2.101

Question 11

A researcher states the following hypotheses: H0: μTime 1 = μTime 2 and H1: μTime 1 ≠ μTime 2. Assuming she collects data from 10 people, what is the appropriate critical value (α = .05; two-tailed)?

Accepted Answer

A)  1.833 
B)  2.228 
C)  2.262 
D)  3.250

Question 12

A study tests the difference between 15 ants and 15 ladybugs. In this example, the degrees of freedom is ______.

Accepted Answer

A)  14 
B)  15 
C)  28 
D)  30

Question 13

A study compares 5 Democrats and 5 Republicans and obtains a value of 2.27 for the t-statistic. For α = .05 (two-tailed), which of the following is the correct way to present this analysis?

Accepted Answer

A)  t(10) = 2.27, p > .05 
B)  t(8) = 2.27, p  .05

Question 14

You are ______ likely to reject the null hypothesis when the alternative hypothesis is ______.

Accepted Answer

A)  less; non-directional 
B)  equally; non-directional 
C)  more; non-directional 
D)  less; directional

Question 15

Holding all else constant, the smaller the standard deviations, the ______ the standard error of the difference  and the ______ the value of the t-statistic (t).

Accepted Answer

A)  larger; larger 
B)  larger; smaller 
C)  smaller; larger 
D)  smaller; smaller

Question 16

The mean of the sampling distribution of the difference is equal to ______.

Accepted Answer

A)  the population mean (μ) 
B)  0 
C)  1 
D)  the standard error of the difference

Question 17

This distribution illustrates a ______.

Accepted Answer

A)  directional null hypothesis 
B)  non-directional alternative hypothesis 
C)  non-directional null hypothesis 
D)  directional alternative hypothesis

Question 18

For a sample of 20 participants, t = 2.500 (α = .05; two-tailed), what would be the decision about the null hypothesis?

Accepted Answer

A)  The null hypothesis could be neither rejected nor accepted. 
B)  The null hypothesis would not be rejected. 
C)  The null hypothesis would be rejected. 
D)  The null hypothesis would need to be retested.

Question 19

What did the researcher do to cause the change in the shaded regions in the two distributions?

Accepted Answer

A)  She changed alpha from .05 to .01. 
B)  She changed alpha from .05 to .10. 
C)  She increased the size of her sample. 
D)  She changed from a non-directional to a directional alternative hypothesis.

Question 20

A professor hands out a quiz 1 to the 30 students in her course, after that the students are given a study session before quiz 2. In analyzing this data, how should the null hypothesis be stated?

Accepted Answer

A)  µ1 = µ2 
B)  µD ≠ 0 
C)  Quiz1 = Quiz2 
D)  µD = 0

Exam 9: Testing the Difference Between Two Means

The t statistic can only be a positive number.

Mary and Joe conduct two separate studies. By an amazing coincidence, they obtain exactly the same sample means and standard deviations. However, Mary's sample is twice as large as Joe's. Which of these is true?

In making the decision to reject the null hypothesis, what would happen if you were to change α from .05 to .01?

The variability of the sampling distribution of the difference is measured by the ______.

A study tests the difference between 20 Democrats and 20 Republicans. In this example, the degrees of freedom is equal to ______.

A researcher calculates the t-test for independent means and reports the following result: t(48) = 2.97, p < .01. This research study consisted of a TOTAL of ______ participants.

A researcher hypothesizes that there is a difference in level of fear of crime for the elderly and young adults. In conducting an analysis to test this hypothesis, how might the alternative hypothesis be stated?

In which of the following situations would you be most likely to set alpha at .10 rather than the traditional .05?

A researcher states the following hypotheses: H₀: μDogs = μCats and H₁: μDogs ≠ μ Cats. Assuming she collects data from 9 dogs and 9 cats, what is the appropriate critical value?

A researcher states the following hypotheses: H₀: μTime 1 = μTime 2 and H₁: μTime 1 ≠ μTime 2. Assuming she collects data from 10 people, what is the appropriate critical value (α = .05; two-tailed) ?

A study tests the difference between 15 ants and 15 ladybugs. In this example, the degrees of freedom is ______.

A study compares 5 Democrats and 5 Republicans and obtains a value of 2.27 for the t-statistic. For α = .05 (two-tailed) , which of the following is the correct way to present this analysis?

You are likely to reject the null hypothesis when the alternative hypothesis is .

Holding all else constant, the smaller the standard deviations, the the standard error of the difference and the the value of the t-statistic (t) .

The mean of the sampling distribution of the difference is equal to ______.

This distribution illustrates a ______.

For a sample of 20 participants, t = 2.500 (α = .05; two-tailed) , what would be the decision about the null hypothesis?

What did the researcher do to cause the change in the shaded regions in the two distributions?

A professor hands out a quiz 1 to the 30 students in her course, after that the students are given a study session before quiz 2. In analyzing this data, how should the null hypothesis be stated?

Exam 9: Testing the Difference Between Two Means

The t statistic can only be a positive number.

Mary and Joe conduct two separate studies. By an amazing coincidence, they obtain exactly the same sample means and standard deviations. However, Mary's sample is twice as large as Joe's. Which of these is true?

In making the decision to reject the null hypothesis, what would happen if you were to change α from .05 to .01?

The variability of the sampling distribution of the difference is measured by the ______.

A study tests the difference between 20 Democrats and 20 Republicans. In this example, the degrees of freedom is equal to ______.

A researcher calculates the t-test for independent means and reports the following result: t(48) = 2.97, p < .01. This research study consisted of a TOTAL of ______ participants.

A researcher hypothesizes that there is a difference in level of fear of crime for the elderly and young adults. In conducting an analysis to test this hypothesis, how might the alternative hypothesis be stated?

In which of the following situations would you be most likely to set alpha at .10 rather than the traditional .05?

A researcher states the following hypotheses: H0: μDogs = μCats and H1: μDogs ≠ μ Cats. Assuming she collects data from 9 dogs and 9 cats, what is the appropriate critical value?

A researcher states the following hypotheses: H0: μTime 1 = μTime 2 and H1: μTime 1 ≠ μTime 2. Assuming she collects data from 10 people, what is the appropriate critical value (α = .05; two-tailed) ?

A study tests the difference between 15 ants and 15 ladybugs. In this example, the degrees of freedom is ______.

A study compares 5 Democrats and 5 Republicans and obtains a value of 2.27 for the t-statistic. For α = .05 (two-tailed) , which of the following is the correct way to present this analysis?

You are ______ likely to reject the null hypothesis when the alternative hypothesis is ______.

Holding all else constant, the smaller the standard deviations, the ______ the standard error of the difference and the ______ the value of the t-statistic (t) .

The mean of the sampling distribution of the difference is equal to ______.

This distribution illustrates a ______.

For a sample of 20 participants, t = 2.500 (α = .05; two-tailed) , what would be the decision about the null hypothesis?

What did the researcher do to cause the change in the shaded regions in the two distributions?

A professor hands out a quiz 1 to the 30 students in her course, after that the students are given a study session before quiz 2. In analyzing this data, how should the null hypothesis be stated?

A researcher states the following hypotheses: H₀: μDogs = μCats and H₁: μDogs ≠ μ Cats. Assuming she collects data from 9 dogs and 9 cats, what is the appropriate critical value?

A researcher states the following hypotheses: H₀: μTime 1 = μTime 2 and H₁: μTime 1 ≠ μTime 2. Assuming she collects data from 10 people, what is the appropriate critical value (α = .05; two-tailed) ?

You are likely to reject the null hypothesis when the alternative hypothesis is .

Holding all else constant, the smaller the standard deviations, the the standard error of the difference and the the value of the t-statistic (t) .