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PRE-ELECTION POLLS IN 2012 Clyde Tucker. Outline Review of the Polls Issues in Pre-election Polls Electoral Choice in Survey Research.

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Presentation on theme: "PRE-ELECTION POLLS IN 2012 Clyde Tucker. Outline Review of the Polls Issues in Pre-election Polls Electoral Choice in Survey Research."— Presentation transcript:

1 PRE-ELECTION POLLS IN 2012 Clyde Tucker

2 Outline Review of the Polls Issues in Pre-election Polls Electoral Choice in Survey Research

3 MoE Obama Romney Spread Final Result D RCP Average 10/31-11/ D Politico/GWU Tie Rasmussen R IBD/TIPP D CNN/OR Tie Gallup R ABC/Wash. Post D Monmouth/Braun Tie NBC/Wall St J D Pew Research D

4 State RCP Average Spread Final Result Spread Obama Romney Obama Romney OH D D FL R D VA D D NH D D NC R R MI D D WI D D PA D D IA D D CO D D NV D D

5 Kaine Allen Spread VA Final Result D RCP Avg D Warren Brown Spread MA Final Result D RCP Avg D Heitkamp Berg Spread ND Final Result D RCP Avg, R Tester Rehberg Spread MT Final Result D RCP Avg R

6 Issues in Pre-election Polls Cell Phone Only Households –At least a third of households are cell only –Increases to about half when “cell mostly” –Excluding cell-only households restricts access to young voters 22% of adults in the Census are years old 0nly 6% of respondents are in Pew landline samples

7 Outline Increasing Nonresponse –Over the last two decades response rates n telephone surveys have been in rapid decline –Contributing to this decline have been the following A growing number of single-person households Changing technologies—answering machines, caller ID and the decline in the number of households with a landline

8 8www.people-press.org Steep Decline in Response Rates Over the Past 15 Years Rates calculated using AAPOR’s CON2, COOP3 and RR3. Rates are typical for Pew Research surveys conducted in each year. From “Reflections on Election Polling and Forecasting from Inside the Boiler Room,” Prepared for the CNSTAT public seminar by Scott Keeter. ”

9 Outline –Peter Miller, a former President of AAPOR, said trying to weight away nonresponse can create unknown errors –Even if the demographics of telephone respondents are similar to the voting age population as a whole, there can still be substantial differential nonresponse

10 Pew Research Standard survey Governme nt surveys In the past year… % Volunteered for an organization 5527 Contacted a public official 3110 Talked with neighbors weekly or more From “Reflections on Election Polling and Forecasting from Inside the Boiler Room,” Prepared for the CNSTAT public seminar by Scott Keeter. But Sizeable Differences in Civic and Political Engagement

11 Outline –The biggest problem, of course, would come from differential nonresponse by vote choice –There has been evidence of this in exit polls –However, one saving grace may be that nonrespondents are less likely to vote –This is probably true given the lack of civic engagement

12 Outline Determining Likely Voters –Likely voter screens are usually based on answers to a series of questions, including political interest, past voting history, length of time in the community, and likelihood of voting –The likely voter screen is used either to exclude respondents with a low score or to assign a probability of voting to each respondent, often aided by information from voter validation studies. – But, what is the result?

13 Outline –In his recent presentation at NAS, Scott Keeter provided evidence that using a likely voter screen resulted in a difference between the candidates that was closer to the final result in the 2008 Presidential Election –Also, as we already have seen, the difference between the candidates among likely voters in the final 2012 Pew poll was very close to the actual result –Yet, this is not always the case

14 Outline –Registered voter numbers should exhibit less variance than likely voter numbers –Begin with a baseline for both registered voters and likely voters shortly before the conventions –Track both series up until election day –Examine the variance of the likely voter series, determining which screener questions contribute most to the variance –Carry out this exercise over several elections

15 Outline Allocating Undecideds – There are essentially three ways to allocate the undecideds Evenly divide them between the candidates (most often the two leading ones) Assign undecideds proportionately based upon the proportions for each candidate among the decided voters Assign an undecided voter based on the characteristics of the voter (models will differ depending on the analyst) –Again, the correct allocation is probably dependent on the specific election context

16 An Example from Nate Silver Presidential Vote in Virginia Obama Romney Polling Avg Adj. Polling Avg State Fundamentals Now Cast Overall Avg Projected Vote Allocated Undecideds

17 Outline House effects –Political bias—incorporated at any stage –Methodological sophistication –Funding –Mode Interviewer conducted (dual frame or only landline) Robo calls Internet polls

18 The Tyranny of the Electoral Choice in Survey Research The importance of electoral choice –Very important behavior--the best known product of survey research (unemployment rate probably in second place) –A gold standard is available The problem with electoral choice –Only one of many products of survey research –Binary choice –Constrained distribution At least 40% (probably more now) can be initially assigned to each party In poll with 1000 respondents, margin of error (+/- 3%) covers a good part of the remaining difference between the candidates

19 An Interesting Alternative to a National Presidential Poll Using state-based models to predict the electoral vote margin Two methods offered by Nate Silver at the New York Times and Drew Linzer at Emory University Both correctly predicted the electoral vote margin relying, in part, on averages of polls in individual states

20 Silver’s method combines an overall measure of economic performance, state polls, and recent state electoral history to forecast each state race He then uses these estimates to determine the most likely electoral vote margin Although the economic measure and past state voting history have a great effect early in the campaign season, they decline in importance relative to the polls as the election draws near

21 Linzer’s method starts with a prior based on a modified structural forecast and then relies on only the state polls and the recent state electoral history in a process he calls Dynamic Bayesian Forecasting This is a hierarchical model that borrows strength from trends in the frequently polled states to make estimates of states with little polling that also incorporates random-walk priors

22 As in Silver’s model, electoral history takes a back seat to the polls in the model as the election approaches Both methods rely on simulations of model predictions of the electoral outcome to establish a probability distribution for determining the chance that each candidate has of winning


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