Question 1

When effect size is small, a small sample is typically sufficient to identify important differences.

Accepted Answer

A) True 
 B)False  False

Question 2

Power is defined as the

Accepted Answer

A)  probability of rejecting a true null hypothesis. 
B)  probability of accepting a false null hypothesis. 
C)  probability of rejecting a false null hypothesis. 
D)  Power is not related directly to the null hypothesis. 
A)  probability of rejecting a true null hypothesis. 
B)  probability of accepting a false null hypothesis. 
C)  probability of rejecting a false null hypothesis. 
D)  Power is not related directly to the null hypothesis. C

Question 3

The probability of rejecting a false null hypothesis is called

Accepted Answer

A)  statistics. 
B)  power. 
C)  statistical significance. 
D)  prediction. 
A)  statistics. 
B)  power. 
C)  statistical significance. 
D)  prediction. B

Question 4

If power = .75, there is a 25% chance of correctly rejecting the null hypothesis.

Accepted Answer

A) True 
 B)False

Question 5

You are on an Institutional Animal Care and Use Committee (IACUC) at your school. You receive a request to run an animal study where the power will be .40. Do you approve the study?

Accepted Answer

A)  Yes; this indicates the study has a 60% chance of obtaining a significant result 
B)  No; this indicates the study has only a 40% chance of obtaining a significant result. 
C)  Yes; this indicates the results will be incorrect only 40% of the time. 
D)  No; this indicates the study has a 40% chance of missing the significant result. 
A)  Yes; this indicates the study has a 60% chance of obtaining a significant result 
B)  No; this indicates the study has only a 40% chance of obtaining a significant result. 
C)  Yes; this indicates the results will be incorrect only 40% of the time. 
D)  No; this indicates the study has a 40% chance of missing the significant result.

Question 6

A Type II error is the probability of

Accepted Answer

A)  finding a difference that is really there. 
B)  finding a difference that is not really there. 
C)  not finding a difference that is really there. 
D)  not finding a difference that is not really there. 
A)  finding a difference that is really there. 
B)  finding a difference that is not really there. 
C)  not finding a difference that is really there. 
D)  not finding a difference that is not really there.

Question 7

Power is the probability of correctly rejecting the null hypothesis.

Accepted Answer

A) True 
 B)False

Question 8

Is it more meaningful to find a significant difference with a relatively small sample size or with a relatively large sample size?

Accepted Answer

A)  It points to a more robust difference if you have a small sample size. 
B)  It points to a more substantial difference if you have a large sample size. 
C)  The two differences are equally substantial. 
D)  We can't tell anything about the size of the effect from what is given here. 
A)  It points to a more robust difference if you have a small sample size. 
B)  It points to a more substantial difference if you have a large sample size. 
C)  The two differences are equally substantial. 
D)  We can't tell anything about the size of the effect from what is given here.

Question 9

The effect size (
  ) is

Accepted Answer

A)  the size of the difference between the means. 
B)  the size of the samples you use. 
C)  the difference between the means scaled by the size of the standard deviation. 
D)  the width of the distribution. 
A)  the size of the difference between the means. 
B)  the size of the samples you use. 
C)  the difference between the means scaled by the size of the standard deviation. 
D)  the width of the distribution.

Question 10

An English teacher believes his method of teaching grammar, usage, and mechanics is superior to most other approaches. He plans to compare his students' average score on a standardized test to the national average. Assuming a medium effect size, 20 students in his class, and α = .05, what is power?

Accepted Answer

The answer of An English teacher believes his method of...

Question 11

A pediatrician is interested in determining if cognitive development scores are lower for low-birthweight infants than normal infants. She has 49 active cases involving low-birthweight infants from who she could collect data to compare to the national average. What would power be assuming the following effect sizes and α = .05? 
a. 
   =.20 
b. 
   =.50 
c. 
   =.80

Accepted Answer

a. .29 
b.

Question 12

Knowledgeable and unbiased observers have generally noted, and studies have reliably shown, that psychotherapy is better than no treatment at all for a person who is seriously depressed. My study failed to find a difference. From this I can conclude that

Accepted Answer

A)  psychotherapy really is not effective. 
B)  my study must have been poorly done. 
C)  my study may have lacked sufficient power to find a difference. 
D)  other psychologists don't know what they are talking about. 
A)  psychotherapy really is not effective. 
B)  my study must have been poorly done. 
C)  my study may have lacked sufficient power to find a difference. 
D)  other psychologists don't know what they are talking about.

Question 13

Sometimes different experimenters find different results because of

Accepted Answer

A)  chance. 
B)  small sample sizes. 
C)  "the cruel hand of fate." 
D)  all of the above 
A)  chance. 
B)  small sample sizes. 
C)  "the cruel hand of fate." 
D)  all of the above

Question 14

Which of the following represents Cohen's rough estimates of small, medium, and large effect sizes?

Accepted Answer

A)  .20, .50, .80 
B)  .00, .50, 1.50 
C)  .80, .50, .20 
D)  .40, .50, .60 
A)  .20, .50, .80 
B)  .00, .50, 1.50 
C)  .80, .50, .20 
D)  .40, .50, .60

Question 15

In the text the author complained about being asked "how many subjects do I need." His point was that this is a more complex question than it seems because you need to consider

Accepted Answer

A)  how many subjects you have available. 
B)  how many subjects it would be convenient to run. 
C)  how many subjects your animal welfare committee will accept. 
D)  what the treatment effect is. 
A)  how many subjects you have available. 
B)  how many subjects it would be convenient to run. 
C)  how many subjects your animal welfare committee will accept. 
D)  what the treatment effect is.

Question 16

Which of the following is involved in the calculation of power?

Accepted Answer

A)  alpha (α) 
B)  the standard deviation 
C)  the difference between the means 
D)  All of the above are involved. 
A)  alpha (α) 
B)  the standard deviation 
C)  the difference between the means 
D)  All of the above are involved.

Question 17

The effect size is generally denoted by

Accepted Answer

A)  beta (β). 
B)  alpha (α). 
C)  d-hat (   ). 
D)  delta (δ). 
A)  beta (β). 
B)  alpha (α). 
C)  d-hat (   ). 
D)  delta (δ).

Question 18

Suppose that in the previous question the 95% confidence interval on the difference between group means was computed to be 2.63 ≤  µ1 -  µ2  ≤ 13.37. What can we conclude about the null hypothesis of no treatment effect?

Accepted Answer

A)  The difference is significant. 
B)  The difference is not significant. 
C)  The treatment doesn't work. 
D)  Confidence intervals are totally unsuited to this question. 
A)  The difference is significant. 
B)  The difference is not significant. 
C)  The treatment doesn't work. 
D)  Confidence intervals are totally unsuited to this question.

Question 19

Calculate effect size given the following information: 
a. μ  1  =30,  μ 2 = 35, σ = 3 
b. μ  1  =40,  μ 2 = 30, σ =10 
c. μ 1=100,  μ 2 = 98, σ = 5

Accepted Answer

a. 1.67 
b

Question 20

Given the following values for δ, what is power assuming α = .05? 
a. δ = 1.55 
b. δ = 3.60 
c. δ = 2.65

Accepted Answer

a. .34 
b.

When effect size is small, a small sample is typically sufficient to identify important differences.

Power is defined as the

The probability of rejecting a false null hypothesis is called

If power = .75, there is a 25% chance of correctly rejecting the null hypothesis.

You are on an Institutional Animal Care and Use Committee (IACUC) at your school. You receive a request to run an animal study where the power will be .40. Do you approve the study?

A Type II error is the probability of

Power is the probability of correctly rejecting the null hypothesis.

Is it more meaningful to find a significant difference with a relatively small sample size or with a relatively large sample size?

The effect size ( ) is

An English teacher believes his method of teaching grammar, usage, and mechanics is superior to most other approaches. He plans to compare his students' average score on a standardized test to the national average. Assuming a medium effect size, 20 students in his class, and α = .05, what is power?

Knowledgeable and unbiased observers have generally noted, and studies have reliably shown, that psychotherapy is better than no treatment at all for a person who is seriously depressed. My study failed to find a difference. From this I can conclude that

Sometimes different experimenters find different results because of

Which of the following represents Cohen's rough estimates of small, medium, and large effect sizes?

In the text the author complained about being asked "how many subjects do I need." His point was that this is a more complex question than it seems because you need to consider

Which of the following is involved in the calculation of power?

The effect size is generally denoted by

Suppose that in the previous question the 95% confidence interval on the difference between group means was computed to be 2.63 ≤ µ1 - µ2 ≤ 13.37. What can we conclude about the null hypothesis of no treatment effect?

Calculate effect size given the following information: a. μ ₁ =30, μ ₂ = 35, σ = 3 b. μ ₁ =40, μ ₂ = 30, σ =10 c. μ ₁=100, μ ₂ = 98, σ = 5

Given the following values for δ, what is power assuming α = .05? a. δ = 1.55 b. δ = 3.60 c. δ = 2.65

Introduction

Basic Concepts

Displaying Data

Measures of Central Tendency

Measures of Variability

The Normal Distribution

Basic Concepts of Probability

Sampling Distributions and Hypothesis Testing

Correlation

Regression

Multiple Regression

Hypothesis Tests Applied to Means: One Sample

Hypothesis Tests Applied to Means: Two Related Samples

Hypothesis Tests Applied to Means: Two Independent Samples

One-Way Analysis of Variance

Factorial Analysis of Variance

Repeated-Measures Analysis of Variance

Chi-Square

Nonparametric and Resampling Statistical Tests

Meta-Analysis

Filters

Exam 15: Power

When effect size is small, a small sample is typically sufficient to identify important differences.

Power is defined as the

The probability of rejecting a false null hypothesis is called

If power = .75, there is a 25% chance of correctly rejecting the null hypothesis.

You are on an Institutional Animal Care and Use Committee (IACUC) at your school. You receive a request to run an animal study where the power will be .40. Do you approve the study?

A Type II error is the probability of

Power is the probability of correctly rejecting the null hypothesis.

Is it more meaningful to find a significant difference with a relatively small sample size or with a relatively large sample size?

The effect size ( ) is

Knowledgeable and unbiased observers have generally noted, and studies have reliably shown, that psychotherapy is better than no treatment at all for a person who is seriously depressed. My study failed to find a difference. From this I can conclude that

Sometimes different experimenters find different results because of

Which of the following represents Cohen's rough estimates of small, medium, and large effect sizes?

In the text the author complained about being asked "how many subjects do I need." His point was that this is a more complex question than it seems because you need to consider

Which of the following is involved in the calculation of power?

The effect size is generally denoted by

Suppose that in the previous question the 95% confidence interval on the difference between group means was computed to be 2.63 ≤ µ1 - µ2 ≤ 13.37. What can we conclude about the null hypothesis of no treatment effect?

Calculate effect size given the following information: a. μ 1 =30, μ 2 = 35, σ = 3 b. μ 1 =40, μ 2 = 30, σ =10 c. μ 1=100, μ 2 = 98, σ = 5

Given the following values for δ, what is power assuming α = .05? a. δ = 1.55 b. δ = 3.60 c. δ = 2.65

Introduction

Basic Concepts

Displaying Data

Measures of Central Tendency

Measures of Variability

The Normal Distribution

Basic Concepts of Probability

Sampling Distributions and Hypothesis Testing

Correlation

Regression

Multiple Regression

Hypothesis Tests Applied to Means: One Sample

Hypothesis Tests Applied to Means: Two Related Samples

Hypothesis Tests Applied to Means: Two Independent Samples

One-Way Analysis of Variance

Factorial Analysis of Variance

Repeated-Measures Analysis of Variance

Chi-Square

Nonparametric and Resampling Statistical Tests

Meta-Analysis

Filters

Calculate effect size given the following information: a. μ ₁ =30, μ ₂ = 35, σ = 3 b. μ ₁ =40, μ ₂ = 30, σ =10 c. μ ₁=100, μ ₂ = 98, σ = 5