Philip J. Trounstine
The Science of Political Polling
Phil Trounstine is Director of the Survey and Policy
Research Institute (SPRI),
a self-supporting, non-profit entity located at San Jose
State University that
provides consulting services in the areas of survey and
policy research,
analysis and report generation to business, government,
civic and political
organizations. The Institute provides mastery in
sampling technique, instrument
design, quantitative and qualitative research,
professional interviewing, data
analysis, report presentation and multicultural research.
The use of polling to gauge the impact of statements
from political candidates
on the electorate has been widespread during this years
presidential race, and
accusations of deliberately biased polling have been
made by both campaigns.
Phil, the former political editor of the San Jose
Mercury News, will give an
overview of the science behind polling, give his sense
of the level of bias in
the polls, and comment on how polling results may
influence how voters make
their selections on election day.
Phil began his talk by explaining that the SPRI first developed its
name by gathering information on California consumer confidence using
the same polling techniques that the University of Michigan developed
to gather national data on the same subject. Since then they have done
a lot of polling for a variety of clients. Part of his goal in basing
the institution at San Jose State was to help give the school more of
the kind of name it deserves, especially considering that a lot of the
worker bees that keep Silicon Valley moving forward come out of that
school.
He then quoted a number of different national polls that showed Bush
ahead of Kerry in the race to be the next President by one to two
percent. Then he explained that there are many trick issues associated
with getting good information from people. For example, if you ask
someone what Party they associate with and then whom they will vote
for, the answer is likely to be very predictable. If you put a number
of questions between those, you are more likely to get answers that
actually capture
that persons feelings.
Phil then explained that pollsters generally use randomized lists of
residential land line phone numbers because studies have shown these
are most likely to give answers that are statistically similar to those
of election day, within margins of error. There are companies
that provide such lists in blocks of 1000, evenly distributed
throughout the area codes and prefixes of the State.
Phil said there are some population shifts that are not captured by the
sampling techniques above. For example, young voters are more likely to
only have cell phones. To illustrate this he asked if anybody in the
room had a cell phone and no land line. One person raised his hand
(something less than 5% of the people in the room). Then he told us he
had asked the same question in a classroom at San Jose State, and a
quarter of the students had raised their hands. He said it was possible
that such effects could make poll results different from the outcome of
the election in States like Ohio and Florida that have huge populations
of college students (who have been shown to be more likely to vote for
Kerry).
Tian Harter