Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Power of alternative designs for comparative studies with respect to (a) odds ratio of 0.67 (relative risk = 0.7) and (b) odds ratio of 0.84 (relative risk = 0.85) with ratios of enrollment costs (CE) to visit costs (CV) 2:1, 3:1, and 4:1.
