Wednesday, October 28, 2015

Latest poll still within error margin, but weighting recent polls shows Conway has slightly better chance to win

By Matthew Young
University of Kentucky School of Journalism and Telecommunications

The final Bluegrass Poll released Wednesday evening showed Democrat Jack Conway leading Republican Matt Bevin 45 percent to 40 percent, with an error margin of plus or minus 3.5 percentage points, which applies to each number. Independent Drew Curtis was favored by 6 percent of voters polled, with 10 percent undecided.

With the election Tuesday, Nov. 3, and public polling in the race likely completed, we ran a weighted aggregation on the six public polls done for the race. A weighted aggregation is an average created by assigning varying levels of significance to each set of data. Recent polls are more significant because they reflect the most current feelings of voters, but older polls still have significance because no poll surveys every voter in Kentucky, and subsequent polls may not reflect the views of all demographics or areas. Also, many voters feelings have not changed, so it is important to keep their responses, though they are not as significant as current polls.

In our weighting, each week going back in time was considered 20 percent less significant than the week following it. So in this case, this week’s two polls (the Bluegrass and the Big Red) were weighted at 100 percent significance. Last week would have been 80%, the week before 64%, then 51.2% and so on.

In the weighted aggregation Bevin still trails by 4.44 points, taking 39.71 percent to Conway’s 44.15 percent. Because the aggregation has a larger sample size, its margin of error is only 1.43 percent. This means it can be said with 95 percent certainty -- the standard in polling -- that Conway’s lead over Bevin is between 2.5 and 6.4 points. However, with 9.66 percent undecided, it is still anyone’s race.

Just how big a factor could the undecided voters be? A randomized test for the weighted poll shows that the chance Conway will win is only 50.5 percent, meaning the race is about as certain as a coin flip. A probability test assuming that if undecideds split toward Conway as other voters do, gives him a 51.7 percent chance to win. Splitting undecideds evenly gives him a 51.6 percent chance. If they break 60-40 for Bevin, Conway still has a 50.4 percent chance to win. Undecideds typically lean against incumbents, and Conway is effectively the incumbent in this race. However, voters in the Bluegrass Poll viewed Conway more favorably than Bevin.

Adding to the uncertainty is the fact that 79 percent of the registered voters called by the Bluegrass Poll said they were likely to vote. Turnout is never that high, and election officials and political experts expect turnout to be 30 percent or less. Also, the lack of movement in the race’s polls suggest that most voters have made up their minds, and most undecided voters typically don’t go to the polls.

All this means that the campaigns are putting more effort on turning out their supporters than persuading undecideds. Both Conway and Bevin are following tradition, and kicking off tours of key areas and get-out-the vote events to try to generate interest in the closing days. Conway began a “Moving Kentucky Forward” tour Tuesday morning, with roundtable and meet and greet events in Western Kentucky. Bevin’s get-out-the-vote tour also began Wednesday with stops in Louisville, Somerset, and Columbia. For an election that is expected to have very low voter turnout, the race may depend on which candidate can organize, rally, or excite their voting base.

No comments:

Post a Comment