1. M

    RCT: estimation of total sample size knowing only the percentage of occurrence

    Dear all, I was asked to estimate the minimum sample size to set up a RCT comparing a standard dose technique to detect recurrence of disease vs low-dose technique. It seemed to be reasonably to me to think about differences in sensitivity and to suggest a noninferiority trial comparing the...
  2. A

    conditional probability and trial of experiments

    Consider a medical test for a disease, D. The test mostly gives the right answer, but not always. Say its false-negative rate is 1% and its false-positive rate is 2%, that is, P(y | D) = 0.99; P(n | D) = 0.01; P(y | ¬D) = 0.02; P(n | ¬D) = 0.98. Assume that you perform the test 4 times in a...