Our data derive from the National Survey of Reproductive
and Contraceptive Knowledge, also known as the Fog
Zone survey, which was commissioned by the National
Campaign to Prevent Teen and Unplanned Pregnancy
and conducted by researchers at the Guttmacher Institute
from October 2008 to April 2009. The survey involved a
sample of 1,800 unmarried 18–29-year-olds. Preliminary
fi ndings, as well as a more in-depth description of the
study design and methods, were released in 2010.23
The sample was selected so that the weighted results
are statistically representative of the overall population of
unmarried 18–29-year-old adults, as well as of unmarried
young adults of each gender and race or ethnicity. In all,
177 were reached through random-digit dialing of landline
phone numbers, 903 through a sample of landline
numbers with a high probability of containing unmarried
residents in their 20s and 720 by cell phone. The sample
was stratifi ed by type of phone number (landline vs.
cell phone) and race and ethnicity; black and Hispanic
young adults were oversampled. The fi eld-tested questionnaire,
which was offered in both English and Spanish,
was approved by the Guttmacher Institute’s institutional
review board.
The total sample consisted of 903 men and 897 women.
We restricted our analytic sample to those in a current
sexual relationship (420 men and 499 women). We did
so for two reasons. First, pregnancy ambivalence may be
more common in ongoing relationships than in brandnew
relationships or one-night stands.9 Second, the sexual
relationship variable was the only way to identify those
respondents who likely had been sexually active in the last
month. We also excluded respondents who were pregnant,
actively trying to get pregnant or get a partner pregnant,
or using female or male sterilization. The fi nal sample consisted
of 774 respondents (355 men and 419 women).