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.
The ‘S'-shaped curve with the count of days of drug use on the x axis and estimated risk of developing drug dependence on the y axis. The four parameters that determine the shape of the curve are Pmin, Pmax, PD50 and k. Data from newly incident drug users found in the United States National Surveys on Drug Use and Health, 2002–2011.
