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FA2012, on the top of p. 58, says that power "depends on:
1) total number of endpoints experienced by population
2) difference in compliance between treatment groups (differences in the mean values between groups)
3) size of expected effect"
Could someone please explain what you think each of those three points means?
I have my own interpretation, but I would benefit from someone else's perspective.
I'm guessing that, for #1, as the total number of endpoints increases, power decreases, because it is therefore less likely that any one given conclusion could be drawn.
I feel, with #2, power decreases with an increased difference in compliance between Tx groups, because we're more likely to draw the correct conclusion if compliance is maximized across all participants.
For #3, I'm a bit confused by the wording here. I'm interpreting "size" as synonymous with "significance," or "inclination to cause impact." I would guess that as the size of the expected effect increases, the power also increases, because conclusions that are more tangible or significant to begin with are more likely to be "discovered."
1) total number of endpoints experienced by population
2) difference in compliance between treatment groups (differences in the mean values between groups)
3) size of expected effect"
Could someone please explain what you think each of those three points means?
I have my own interpretation, but I would benefit from someone else's perspective.
I'm guessing that, for #1, as the total number of endpoints increases, power decreases, because it is therefore less likely that any one given conclusion could be drawn.
I feel, with #2, power decreases with an increased difference in compliance between Tx groups, because we're more likely to draw the correct conclusion if compliance is maximized across all participants.
For #3, I'm a bit confused by the wording here. I'm interpreting "size" as synonymous with "significance," or "inclination to cause impact." I would guess that as the size of the expected effect increases, the power also increases, because conclusions that are more tangible or significant to begin with are more likely to be "discovered."