In the context of a randomized controlled trial, we want the power to be: A) Sma
ID: 3313746 • Letter: I
Question
In the context of a randomized controlled trial, we want the power to be:
A)
Small, because this means our likelihood of incorrectly concluding that the treatments differ is low.
B)
Small, because this means that we have a lot of statistical power.
C)
Small, because this means our likelihood of incorrectly concluding that treatments do not differ is low.
D)
Large, because this means that we have a lot of statistical significance.
E)
Large, because this means we are likely to correctly detect a difference between treatments when one exists.
A)
Small, because this means our likelihood of incorrectly concluding that the treatments differ is low.
B)
Small, because this means that we have a lot of statistical power.
C)
Small, because this means our likelihood of incorrectly concluding that treatments do not differ is low.
D)
Large, because this means that we have a lot of statistical significance.
E)
Large, because this means we are likely to correctly detect a difference between treatments when one exists.
Explanation / Answer
In a power calculation, you need to (typically) assume 3 variables and calculate the fourth. You want to calculate sample size, so you need to assume an alpha level, power, and effect size. Alpha and power are usually set at 0.05 and 0.80, respectively. That just leaves effect size. For proportions, your effect size is the two proportions in the control and supplement arms. For your first comparison, you want a power to detect the difference between 0.45 and 0.025 proportions
E)
Large, because this means we are likely to correctly detect a difference between treatments when one exists.
E)
Large, because this means we are likely to correctly detect a difference between treatments when one exists.