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.
Log(
) from the bivariate Poisson model plotted against the covariance diagnostic, cov
from 2008, based upon 1000 simulated datasets for 
, 
and 
. Values at which the covariance diagnostic is negative are shown by crosses. This figure appears in color in the electronic version of this article.
