Question 1

Although hypothesis tests are affected by sample size,sample size has little or no influence on measures of effect size,such as r² or Cohen's d.

Accepted Answer

A) True 
 B)False

Question 2

With α = .05 and df = 8,the critical values for a two-tailed t test are t = ±2.306.Assuming all other factors are held constant,if the df value were increased to df = 20,what would happen to the critical values for t?

Accepted Answer

A)  They would increase in magnitude (move farther from zero) .
B)  They would decrease in magnitude (move closer to zero) .
C)  They would not change.
D)  Impossible to determine without more informationE) B) and C)
F) None of the above

Question 3

The t distribution for df = 4 is flatter and more spread out than the t distribution for df = 20.

Accepted Answer

A) True 
 B)False

Question 4

Compared to a z-score,a hypothesis test with a t statistic requires less information from the population.

Accepted Answer

A) True 
 B)False

Question 5

A sample of n = 25 scores produces a t statistic of t = 2.062.If the researcher is using a two-tailed test,which of the following is the correct statistical decision?

Accepted Answer

A)  The researcher can reject the null hypothesis with α = .05 but not with α = .01.
B)  The researcher can reject the null hypothesis with either α = .05 or α = .01.
C)  The researcher must fail to reject the null hypothesis with either α = .05 or α = .01.
D)  It is impossible to make a decision about H0 without more information.E) All of the above
F) A) and C)

Question 6

A random sample with n = 20 scores has df = 19.

Accepted Answer

A) True 
 B)False

Question 7

Which combination of factors would definitely increase the width of a confidence interval?

Accepted Answer

A)  Increase the sample mean and increase the sample size
B)  Decrease the sample mean and increase the sample size
C)  Increase the sample mean and increase the percentage of confidence
D)  Decrease the sample mean and decrease the percentage of confidenceE) None of the above
F) A) and D) C

Question 8

If two samples,each with n = 20 scores,are selected from the same population and both have the same mean (M = 53)and the same variance (s² = 12),then they will also have the same t statistic.

Accepted Answer

A) True 
 B)False

Question 9

If two samples are selected from the same population,under what circumstances will the two samples have exactly the same t statistic?

Accepted Answer

A)  The samples are the same size and have the same variance
B)  The samples are the same size and have the same mean
C)  The samples have the same mean and the same variance
D)  The samples are the same size and have the same mean and the same varianceE) C) and D)
F) B) and D)

Question 10

If other factors are held constant,which set of sample characteristics is most likely to reject a null hypothesis stating that μ = 80?

Accepted Answer

A)  M = 85 for a sample of n = 25
B)  M = 85 for a sample of n = 100
C)  M = 90 for a sample of n = 25
D)  M = 90 for a sample of n = 100E) All of the above
F) A) and C)

Question 11

With α = .01,the two-tailed critical region for a t test using a sample of n = 16 subjects would have boundaries of ______.

Accepted Answer

A)  t = ±2.602
B)  t = ±2.583
C)  t = ±2.947
D)  t = ±2.921E) B) and C)
F) None of the above

Question 12

If other factors are held constant,as the sample size increases,the estimated standard error decreases.

Accepted Answer

A) True 
 B)False

Question 13

Which set of characteristics will produce the smallest value for the estimated standard error?

Accepted Answer

A)  A large sample size and a small sample variance
B)  A large sample size and a large sample variance
C)  A small sample size and a small sample variance
D)  A small sample size and a large sample varianceE) B) and D)
F) A) and D)

Question 14

A sample with a mean of M = 40 and a variance of s² = 20 has an estimated standard error of 1 point.How many scores are in the sample?

Accepted Answer

A)  4
B)  5
C)  20
D)  21E) All of the above
F) None of the above

Question 15

Which of the following describes what a confidence interval does?

Accepted Answer

A)  It uses a sample mean to estimate the corresponding population mean.
B)  It uses a population mean to predict a sample mean.
C)  It uses a level of confidence to estimate a sample mean.
D)  It uses the sample mean to determine a level of confidence.E) C) and D)
F) A) and B)

Question 16

A sample of n = 4 scores with SS = 48 has a variance of s² = 16 and an estimated standard error of 2.

Accepted Answer

A) True 
 B)False  True

Question 17

If a sample of n = 16 scores is being used to make an 80% confidence interval estimate of the population mean,μ,what value(s) of t should be used?

Accepted Answer

A)  t = 0
B)  t = ±2.131
C)  t = ±1.753
D)  t = ±1.341E) B) and C)
F) A) and C) D

Question 18

For a one-tailed test with α = .05 and a sample of n = 9,the critical value for the t statistic is t = 1.860.

Accepted Answer

A) True 
 B)False

Question 19

Which of the following is not needed to compute a t statistic?

Accepted Answer

A)  A hypothesized value for the population mean
B)  The value of the population variance or standard deviation
C)  The value of the sample mean
D)  The value of the sample variance or standard deviationE) All of the above
F) B) and C)

Question 20

If other factors are held constant,the bigger the sample is,the greater the likelihood of rejecting the null hypothesis.

Accepted Answer

A) True 
 B)False

Exam 9: Introduction to the t Statistic

Although hypothesis tests are affected by sample size,sample size has little or no influence on measures of effect size,such as r² or Cohen's d.

Correct AnswerverifiedShow Answer

With α = .05 and df = 8,the critical values for a two-tailed t test are t = ±2.306.Assuming all other factors are held constant,if the df value were increased to df = 20,what would happen to the critical values for t?

Correct AnswerverifiedShow Answer

The t distribution for df = 4 is flatter and more spread out than the t distribution for df = 20.

Correct AnswerverifiedShow Answer

Compared to a z-score,a hypothesis test with a t statistic requires less information from the population.

Correct AnswerverifiedShow Answer

A sample of n = 25 scores produces a t statistic of t = 2.062.If the researcher is using a two-tailed test,which of the following is the correct statistical decision?

Correct AnswerverifiedShow Answer

A random sample with n = 20 scores has df = 19.

Correct AnswerverifiedShow Answer

Which combination of factors would definitely increase the width of a confidence interval?

Correct AnswerverifiedC

If two samples,each with n = 20 scores,are selected from the same population and both have the same mean (M = 53)and the same variance (s² = 12),then they will also have the same t statistic.

Correct AnswerverifiedShow Answer

If two samples are selected from the same population,under what circumstances will the two samples have exactly the same t statistic?

Correct AnswerverifiedShow Answer

If other factors are held constant,which set of sample characteristics is most likely to reject a null hypothesis stating that μ = 80?

Correct AnswerverifiedShow Answer

With α = .01,the two-tailed critical region for a t test using a sample of n = 16 subjects would have boundaries of ______.

Correct AnswerverifiedShow Answer

If other factors are held constant,as the sample size increases,the estimated standard error decreases.

Correct AnswerverifiedShow Answer

Which set of characteristics will produce the smallest value for the estimated standard error?

Correct AnswerverifiedShow Answer

A sample with a mean of M = 40 and a variance of s² = 20 has an estimated standard error of 1 point.How many scores are in the sample?

Correct AnswerverifiedShow Answer

Which of the following describes what a confidence interval does?

Correct AnswerverifiedShow Answer

A sample of n = 4 scores with SS = 48 has a variance of s² = 16 and an estimated standard error of 2.

Correct AnswerverifiedTrue

If a sample of n = 16 scores is being used to make an 80% confidence interval estimate of the population mean,μ,what value(s) of t should be used?

Correct AnswerverifiedD

For a one-tailed test with α = .05 and a sample of n = 9,the critical value for the t statistic is t = 1.860.

Correct AnswerverifiedShow Answer

Which of the following is not needed to compute a t statistic?

Correct AnswerverifiedShow Answer

If other factors are held constant,the bigger the sample is,the greater the likelihood of rejecting the null hypothesis.

Correct AnswerverifiedShow Answer

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C

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True

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D

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