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.
Weighted mean values at each event time. The mean values are calculated using weights derived from matching. Within matched groups, we weighted each target as 1 and assigned controls weights that summed to 1.
