Chapter 5 Multiple choice questions

* 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