RT Journal
A1 Livingston EH, Elliot AC, Hynan LS, Cao J
T1 CLinical importance of effect size in randomized controlled trials—reply
JF Archives of Surgery
JO Archives of Surgery
YR 2010
FD April 1
VO 145
IS 4
SP 401
OP 401
DO 10.1001/archsurg.2010.48
UL http://dx.doi.org/10.1001/archsurg.2010.48
AB 
I would like to thank Dr Fujita for his thoughtful comments about our editorial. He questions whether it would be best to use the effect size, odds ratio, or number needed to treat for calculating the sample size needed for a clinical trial with binary data outcomes. Cohen's book Statistical Power Analysis for the Behavioral Sciences1 is an excellent source for sample size calculation. It is easy to read and provides numerous sample calculations that facilitate performance of these estimates by investigators who have relatively modest backgrounds in statistical analysis.