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Return to Research Methods Using R 1e Student Resources
Chapter 5 Multiple choice questions
Quiz Content
*
not completed
.
How many participants would you need to test to detect a correlation of
r
=0.5 with power of 0.5 (at α=0.05)? [Hint: you will find the functions in the
pwr
package helpful.]
Less than 10 participants
correct
incorrect
More than 15 participants
correct
incorrect
More than 25 participants
correct
incorrect
More than 50 participants
correct
incorrect
*
not completed
.
How many extra participants would you need to test in the study design from question 1 if the criterion for significance changed to α=0.01?
An extra 10 participants
correct
incorrect
An extra 15 participants
correct
incorrect
An extra 25 participants
correct
incorrect
An extra 50 participants
correct
incorrect
*
not completed
.
What is the smallest effect that can be detected using a t-test with 10 participants per group at a power of 0.8 and α=0.05?
d
= 0.14
correct
incorrect
d
= 0.37
correct
incorrect
d
= 0.98
correct
incorrect
d
= 1.32
correct
incorrect
*
not completed
.
A study testing 20 participants per group produced an effect of
d
=1, which was significant at
p
<0.05. What was the observed power for the study?
Power = 0.01
correct
incorrect
Power = 0.33
correct
incorrect
Power = 0.87
correct
incorrect
Power = 1.54
correct
incorrect
*
not completed
.
What size of effect can be detected at power of 0.3 using a chi-square test with 4 degrees of freedom and 27 observations at α=0.05?
w
= 0.37
correct
incorrect
w
= 0.52
correct
incorrect
w
= 0.73
correct
incorrect
w
= 0.89
correct
incorrect
*
not completed
.
What is the minimum sample size for a chi-square test with 12 degrees of freedom, effect size of 0.3, power of 0.8 and a significance criterion of α=0.001?
N = 35
correct
incorrect
N = 55
correct
incorrect
N = 102
correct
incorrect
N = 349
correct
incorrect
*
not completed
.
For a one-way ANOVA with 5 groups and an effect size of 0.3, what is the power with 24 participants per group (assuming α=0.05)?
Power = 0.03
correct
incorrect
Power = 0.30
correct
incorrect
Power = 0.73
correct
incorrect
Power = 0.83
correct
incorrect
*
not completed
.
What is the smallest effect size that can be detected with power=0.5 using a factorial ANOVA with (3,6) degrees of freedom at α=0.1?
f2 = 0.07
correct
incorrect
f2 = 0.69
correct
incorrect
f2 = 1.07
correct
incorrect
f2 = 1.69
correct
incorrect
*
not completed
.
Imagine a study that measures a dependent variable in 100 individuals of different ages. Which has the greater power – a t-test, where half of the subjects are in each group, or a correlation between age and the dependent variable? Assume an effect size of 0.4, and a significance level of α=0.05.
The correlation has the greater power
correct
incorrect
The t-test has the greater power
correct
incorrect
Both designs have exactly the same power
correct
incorrect
It depends if the t-test is paired or independent
correct
incorrect
*
not completed
.
Which of the following has the greatest statistical power?
A one-sample t-test with 12 observers, α=0.05, and effect size d=0.4
correct
incorrect
A chi-square test with 55 observations, α=0.01, two degrees of freedom, and effect size w=0.2
correct
incorrect
A correlation with 80 observers, α=0.05, and effect size r=0.3
correct
incorrect
A one-way ANOVA with 8 levels, an effect size of 0.3, 12 participants per group, at α=0.05
correct
incorrect
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