Part Two: Design Issues:
Evolution of Sample Survey Methodology
Sample Survey Designs obtain
information by gathering responses to Survey Instruments by
volunteers(Respondents) in some sort of Sample.
Care must be taken in both the
Design and Administration of the Survey Instrument. Care must be taken in the
selection of the Sample.
The current methodology allows for
careful design of Survey Instruments, including review panels and pilot tests,
in which the Survey Instrument is "tested" on a test(or pilot) group.
The experience of the pilot group suggests editing and content changes to the
Survey Instrument. The preferred method of obtaining Respondents is now Random
Selection.
The integration of Psychology and
Educational Research has led to an appreciation of the importance of the
wording and delivery of Survey Instrument Items, as well as the need for
Special Methods when dealing with extremely sensitive items.
The
1936 and 1948 Presidential Polls
A number of important survey
failures stressed the need for Random Sampling. The Literary Digest US
Presidential Poll of 1936 used a non-random sample targeting telephone
directories, automobile registries and the LD subscriber list. Even though 2.4
million respondents were acquired for the poll, the poll failed miserably.
Moreover, the bulk of US voters in the 1936 Presidential Election were
neither automobile owners nor telephone owners nor LD subscribers.
1936: Alf Landon (Incumbent
Governor Kansas (R), father of Nancy Kassebaum ) versus Franklin Delano
Roosevelt (Incumbent President (D), previously Governor New York (D) )
Links for the 1936 LD Poll: 1, 2, 3
Three major polling organizations - Crossley,
Roper and Gallup, suffered poll failures for the 1948 US Presidential
Election. All three organizations drew non-random samples which nicely
resembled the population of US Voters, and all three polls still failed, though
by a small margin. The problem was with the use of quota sampling.In
quota sampling, poll workers are free to use judgment in selecting respondents,
so long as the selected respondents meet quota requirements.
Gallup did two random-sample based
polls for the 1936 US Presidential Election - both samples were much smaller
than the 2.4 million LD Poll Sample. Gallup’s 1936 polls correctly
predicted both the results of the Literary Digest Poll and the Actual
1936 US Presidential Election Results. The bizarre thing is that the Gallup
people did not use Random Sampling in the 1948 US Presidential Election
Poll.
1948: Thomas Dewey(Incumbent Governor New York) versus Truman (Incumbent President (D)
Links for the 1948 Presidential
Polls: 1, 2, 3
After the 1948 Presidential Poll
failures, the importance of random sampling became clear.
More Links
The National Opinion Research Center (NORC)