This preview shows pages 1–2. Sign up to view the full content.
HW5. Effect Size, Power and Sample Size Estimations
Problem 1.
Our research hypothesis is that patients with AT will show
decreased (from 20% to 30%) brain glucose metabolism in the cerebellar
cortex due to decreased inhibitory modulation by Purkinje cells in the
cerebellum when compared with their homozygous non affected siblings.
For this hypothesis, a paired samples ttest will be performed to examine whether A
T patients have decreased brain glucose metabolism in cerebellar cortex in
comparison to their homozygous nonaffected siblings. The standard deviations for
the two groups (AT patients and their unaffected siblings) are estimated to be equal
and is about 10 ~ 15% of the unaffected sibling mean brain glucose metabolism in
the cerebellar cortex. Ten AT patients and 10 of their unaffected siblings will be
recruited for the study. Please answer the following questions.
1.
Given a conservative estimation of a correlation of 0.5 between sibling pairs,
please prove that the estimated standard deviation of the paired differences is
also 10 to 15% of the nonaffected sibling mean.
2.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview. Sign up
to
access the rest of the document.
 Fall '10
 WeiZhu

Click to edit the document details