Cell Phone Only Population

Brian Schaffner over at Pollster.com provides some interesting insight into the Cell Phone Only population. He ran a multinomial logit model based on Pew Survey data to control for a host of demographic factors to see if preferences were the same. Despite an extraordinarily inclusive list of controls (even party ID), he found there to still be differences among the CPO and landline populations (though not statistically significant if you look at his 90% CIs carefully).

The most interesting thing to me is the staggering difference in sampling errors for each of the groups. Look at how much wider the 90% intervals are for the CPOs than the landliners. I'm not sure what exactly we can take that to be indicative of in the populations, but it certainly is fascinating.

While I want to agree with the results on a gut level, I have some concerns about the structure of his model. When I checked out the STATA output Schaffner provides, one thing that stuck out to me was the p-value of .845 on the age variable predicting the McCain/lean outcome relative to the base of Obama. I'm not sure if there might be some multicolinearity issues here. I'm going to download the data myself and play around some. I'm off to lunch now, but soon I will revisit this. I'll report back later.

Senate Debate on Defense

Harvard's Social Science Statistics Blog linked to this really cool visualization. It depicts the change in partisan frequency of different terms in Senate debates on defense from 1997-2004. I've posted the video below. The absence of partisanship post-9/11 and then surge around Iraq is really cool to see - even if it is hardly profound.

America's Most Accurate Pollster

I missed this from Mid-December, but I can't help but comment...

Investor's Business Daily put out an editorial declaring their IBD/TIPP poll the best in the nation - again. They called the popular vote margin to the decimal in 2008 and were the closest (of by 0.3%) in 2004. I extend all due congratulations - particularly in an astute allocation of the undecideds, but I just love this link...

Well they certainly were unique in calling the 18-24 year old vote for McCain 74%-22% in late October. Campus was CRAZY that week...

Cell Phones and Surveys

Behind the Numbers ran a post by Jennifer Agiesta on cell phone users and surveys that caught my interest. She aggregated their tracking poll data and looked at the pool to study the effect of cell phones on sampling. She makes two fascinating statements that I've seen before, and I take issue with both:

1. The six versus nine point margin difference between the landline only sample and the complete one with cells is not statistically significant.

2. Weighting the landline sample to the age composition of the exit poll takes care of the discrepancy.

Both of these points are flawed. On the first point, I doubt that the difference is insignificant. The daily margin of error might be three points but these numbers are from aggregated tracking. The margin of error has to be pretty small. But even so the argument is flawed. If I didn't know the results but you asked me which candidate's supporters would be under-represented in a landline only sample, I would be a fool not to pick Obama. The margin of error is a function of the random and unbiased variation we can expect from the nature of proper sampling. Since we can predict the direction of effect of not sampling cell phones, it is specious to compare the size of the effect to the unbiased error we can expect to see. The margin works both ways. One day the sample might advantage the Democrat, and the next it could be the Republican. In a given election cycle, the cell vote does not change direction randomly as a bloc (per the currently accepted theories of the cell vote). Adding in the cell sample changed the margin of victory by three percentage points. That's a decent amount.

In sum, error is random, and bias is not. It is senseless to compare one to the other to downplay its importance.

The second point is a dangerous one. It leads to practices that cause inaccuracy. It trends toward the idea that undersampling and weighting to counter is always an acceptable way of correcting for a cell bias. First, putting a particular weight on cell user turnout is a tricky game. Age corrected the discrepancy for McCain-Obama, but what about other candidate pairs, issues and other poll questions? Second, it justifies undersampling that leads to absurd results. Check that link out. McCain beating Obama 74-22 in the 18-24 vote? There's no way.

Challenged Ballots in Minnesota

Minnesota Public Radio has published many of the challenged ballots in the recount there. Rounds 1 2 3 and 4. I understand that some people (given the overall volume) are bound to change their minds and want to scratch out a choice. However, if a voter fails to follow clear and explicit directions to fill in the oval and only the oval for all contests on the ballot (witness below), that voter's ballot should not be counted.

I suppose for me the most agitating part of all of this comes to mind when I reflect on my roll-off studies. Maybe instead of actual trends resulting from political institutions, it's all just trends in lunacy and oddity. Why would someone randomly abstain from a string of elections only to continue on the ballot later? Might as well figure out why someone chose to take the time to write in "Lizard People" for every write-in slot, and not vote for "Lizard People" for Senate. Oh democracy, how much better you are than the alternatives, but how revealing you are of the people.

Lobbying and Bailout Size

This graph is floating around a bit after Lee Drutman submitted some interesting analysis to The Monkey Cage. I think Andrew Gelman makes a good point that we're looking at some serious selection bias here, and it would be nice to see more zero bailout points to get a better idea of overall lobbying expenditures. Also, as one of the commenters points out, without AIG, there is arguably not much of a relationship there. Pretty graph, but I wouldn't worry about it too much. The AIG lobbying-bailout outlier simply as a relationship between size of bailout and size of assets (Y-axis only) is particularly interesting though. 

Ballot Roll-Off

As promised in my first post, here's the deal with undervoting/roll-off. First, the definition is pretty simple for those not familiar. Roll-off is the phenomenon of voters not completing a ballot with a selection in each contest. It tends to occur more towards the bottom of the ballot in races like "Soil and Water Conservation District Supervisor."

Obviously, this year I was pretty interested in this phenomenon as it affected those of us down the ballot from Barack Obama. Many people were expecting landslides down the ballot for Democrats. We wanted an empirical estimate of what it would be, and more importantly, if it would be. Would there be an Obama wave to ride for the rest of the Democratic Party? Are young/AA voters more likely to roll off of the ballot?

From my analysis of previous elections, the answer to that exact question was no. What was frightening, however, was the nuance. While young and/or AA voters do not roll off at a rate greater than average voters, newly registered young and AA voters were very much more likely to roll off in the 2008 primary in NC. Simply put, there would be a downballot Obama wave, we just needed to learn how to surf it and make sure it got all the way to shore. That's why you saw all kinds of advocacy of the straight party ticket beyond standard turnout efforts. Because we knew turnout was not enough, and we knew by how much.

This study triggered my academic interest in the roll-off phenomenon. I just finished a paper studying the phenomenon in NC judicial elections and proposing an informal model of how to think of roll-off in a functional manner as it occurs within a single ballot. It's rather informal, so don't be surprised by the tone or absence of a thorough lit-review. If anyone is interested, here it is. Let me know in the comments section if you see anything you contest or have anything to say. It is, to say the least, a working paper that I hope to develop over the course of the next semester.