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.
χ2 test of differences between adjusted and unadjusted smoking prevalence rates for A) men and B) women at ages 60–69 years (solid line), 70–79 years (dotted line), and 80 or more years (dashed line) in 2007. The horizontal gray line marks the critical value at the 5% level of statistical significance.
