First, there was a general decline in
smoking behavior throughout the 6-year time
span in question,2 so it would be expected that
NSCAW’s smoking rates in 2000 were lower
than were Add Health’s smoking rates in 1994,
making our approach conservative with regard
to CW risk. Second, previous studies have com-
bined youths’ smoking behavior data over the
same time period for both lifetime smoking and
current smoking.12 Finally, tobacco policy
changed little during this time span.