Welcome to all the new readers. Traffic is booming. First, a brief update. Several weeks ago I showed that convention bounces (and other fluct...
Polling conspiracy theories (your response)
Yesterday my colleague Paul Starr brought up points relevant to this discussion: (1) Voter polarization is extreme. In the Presidential race, the fraction who are undecided appears to be extremely low in 2012. The Meta-analysis indicates that as few as 2% of voters are undecided (i.e. a 4% range in the Meta-margin). (2) A May 2012 Pew Center study showed a response rate of just 9% in phone surveys, down dramatically from even 2009. Holy moly. (3) This is the first year for Citizens United and the resulting unlimited campaign finance to have an effect. I will return to some of these topics in coming weeks.
In yesterday’s comments, both old and new topics were brought up. One subject does not affect poll analysis, but is of extreme importance: campaign finance. I offer a few responses to comments, sorted by subject. Click on the boldface titles to learn more.
Do polling samples capture the voting public? Problems include distinguishing registered from likely voters, not properly capturing cell-phone-only users, and voter ID/voter suppression laws.
Identifying who is a likely voter (LV) matters, and is more prone to going wrong in off-year elections. I recommend an extensive analysis in 2010 by former pollster Mark Blumenthal at Pollster.com. The difference between registered voters (RVs) and LVs is a problem before Labor Day, after which most pollsters switch to reporting LVs. In past years I have not noticed a shift in the Presidential estimator at that time. It might be hard to see because of short-term swings like convention bounces.
The question of cell-phone sampling comes up repeatedly. To my thinking it is not a real problem, in the sense that in principle it could be fixed by adjustments in survey techniques. However, as I mentioned above, the low response rate problem does give me pause.
Voter ID/voter suppression. For the long term this is a serious issue. It matters the most in very close races. In the 2012 Presidential race it may not be a factor, mainly because Pennsylvania is not in play. But for State/district races, and as a fundamental matter of our democracy, it is a serious issue.
Campaign spending. This is the first year in which the effects of Citizens United will be felt strongly. Campaign spending does not affect poll accuracy, but the polls should be able to measure the effects. I believe it will make the largest difference in Senate, House, and state-level races, where campaigns cost less…for now. There is a reason why Karl Rove’s Crossroads GPS is working at these lower levels – leverage. I believe this is the single most important new issue to watch in 2012.
Technical issues with poll aggregation. Amitabh Lath wanted to know: if we corrected for individual pollster biases, how would we know where to set the scale? Yes, somehow one must anchor this bias, which I called d in the comment thread. One possibility would be to assume that the median ofd is zero. The justification is that on Election Day in 2004 and 2008, the Meta-analysis landed right on the EV result. If one wanted to get fancy, one could create a tool to allow the reader to anchor d using his/her favorite pollster. Even Rasmussen fans would be pleased.
The question came up of why one does numerical simulations. These are good for evaluating a model with lots of “nuisance parameters” (what an excellent name for them!). They are not a means of introducing randomness. However, in my view, when one can, it is better to understand a model well enough to calculate the exact distribution of all possible outcomes. For example, I see no reason for the FiveThirtyEight “Now-cast” to be calculated by simulation. For that, all 2.3 quadrillion electoral possibilities are contained (as they are for my calculation) in this bit of MATLAB haiku: dist= / for i=1:51 / dist=conv(dist, [p(i) 0 0 … 1-p(i)]) / end. For the compulsive, add a few lines for Maine and Nebraska.
If anyone is interested, here a new comment thread below.