Surveys using non-list-based
random sampling
Non-list-based random sampling methods
allow for the selection of a probability-based
sample without the need to actually enumerate
a sampling frame. With traditional surveys,
random digit dialing (RDD) is a non-list-based
random sampling method that is used mainly
for telephone surveys.
There is no equivalent of RDD for
Internet-based surveys. For example, it is not
possible (practically speaking) to generate
random e-mail addresses (see the Issues
and Challenges in Internet-based Survey
Sampling section). Hence, with the exception
of intercept surveys, Internet-based surveys
requiring non-list-based random sampling
depend on contacting potential respondents
via some traditional means such as RDD,
which introduces other complications and
costs. For example, surveyors must either
screen potential respondents to ensure they
have Internet access or field a survey
with multiple response modes. Surveys with
multiple response modes introduce further
complications, both in terms of fielding
complexity and possible mode effects (again,
see the Issues and Challenges in Internetbased
Survey Sampling section).