Now You Know, Not All Polls Are Equal
By Big Tent Democrat
A great favor has been done for those who seem not to realize that the not all polls are equal. The key to polling is the likely voter model. But polling method is also important. An Indiana university poll that used SUSA to do its fieldwork with a poll it designed came out, with a strikingly different result than SUSA did with its own poll. Thus while SUSA has Clinton up 16. The alternate Indiana poll has Obama up 5. How could it happen? Turnout models. Polling methods. Definitions of the relevant universe. Etc.
SurveyUSA conducted two separate, independent, non-commingled election polls in the state of Indiana in the past week, one for SurveyUSA’s TV-news clients (the TV poll) and one for Indiana University Purdue University Fort Wayne (the University poll).
· The TV poll was conducted using “RDD” sample (Random Digit Dial, purchased from SSI of Fairfield CT), which is what SurveyUSA uses on many, but not all, of its statewide election polls.
· The University poll was conducted using “RBS” sample (Registration Based Sample, purchased from Aristotle, of Washington DC), which is what SurveyUSA uses on many, but not all, of its research for non-media clients.
. . . · TV poll interviewing was conducted over 3 consecutive nights that included a weekend (Friday, Saturday, Sunday). · University poll interviewing was conducted over 3 consecutive nights that included only weekdays (Monday, Tuesday, Wednesday).
· The TV questionnaire was shorter. A TV poll “likely voter” could have answered as few as 8 questions (of the 14 total questions) and be included. · A University poll respondent needed to answer at least 26 questions (of the 51 total questions) to be included.
· The “who will you vote for in the Democratic primary for President of the united states” question was asked 3rd in the TV poll. The same question was asked 18th in the University poll.
. . . · TV poll was balanced to most recently available U.S. Census targets for Indiana adults, on gender, age, race and 4 regions defined at the county level by SurveyUSA. To see which Indiana counties are in which region, go here. · University poll was balanced to demographics of the complete voter file for gender, age and 3 regions, each of which region is a cluster of 3 Indiana Congressional Districts. Indiana CD 1, 2 and 3 are combined into a region labeled Northern Indiana. CD 4, 5, and 7 are combined into a region labeled Central Indiana. CD 6, 8 and 9 are combined into a region labeled Southern Indiana.
Any one of these methodological changes, or any combination of them, may contribute to the differences between certain findings in the TV poll and the University poll.
SUSA puts it name on the TV poll. It does not on the University poll which designed the polling method. The SUSA poll is a SUSA poll. The University poll is NOT a SUSA poll.
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