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.
Quartiles are the edges of the box. The edges of the boxes correspond to quartiles; the notches are the standard errors of the median; and the vertical bars to the range.
