Figure 10.
Sample sizes required to detect different degrees of slowing in the rate of atrophy are shown to have a quadratic dependency. Our sample size estimates are based on assuming a 25% slowing of the rate of atrophy, whereas in reality, treatments may slow atrophy to different degrees. Even so, the sample size estimates required to detect a k% slowing of atrophy can be easily derived by multiplying the numbers in this article by (25/k)2. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]
