Dewey Defeats Truman?
The 1948 Dewey vs. Truman presidential election is often credited with
bringing an end to quota sampling. The polls predicted Truman would lose (Gallop: 44%,
Roper 38%). In the end Truman won the election with 50% of the vote (it was actually a
three way race and the other candidates each got less than 50%).
The Chicago Daily Tribune put out its' paper with the headline "Dewey defeats
Truman" in part because of its trust in the polls. But results were late getting in
and the Tribune was facing a strike at the time and had replacement workers in the
printing room (several lines in that issue were printed upside-down). The polls were not
conducted in the last 10 days of the the campaign and many believe that the polls were
correct at the time they were done but public sentiment changed at the last moment. None
the less, Gallop moved to probability sampling after the 1948 election.
