So as we have found out over the past few days, PPP's crosstabs aren't very helpful when it comes to the actual opinions of youth and minorities, despite accurate topline numbers. Is there a way to tell if any other demographics are messed up? Can we still get some interesting information from the massive amount of data available? Yes, and yes.
You will recall this all started with respondents who incorrectly reported their geographic location. This is one thing we actually are fairly certain we know about respondents, because the phone numbers are supposed to be landlines and we know the area code.
If you delve into the demographics of those who misreported their geography, you'll see they are very different from the sample as a whole. For example, about 60% say they're women versus 40% for men. So, either women are more likely to enter an incorrect geography... or people who enter an incorrect geography are far more likely to respond incorrectly to other demographic questions as well.
Are we sure people who enter errors in geography also make errors on other questions? Let's look at one demographic group which is almost defined by its political behavior: Tea Party supporters.
To be a Tea Party supporter is to be against Obama. Yet 7% of Tea Party supporters actually say they will vote for Obama. But if we look at Tea Party supporters who also chose the wrong geography, 19% say they will vote for Obama. The remaining Tea Party supporters are then reduced to 5% support of Obama - the data are closer to what we would expect, but probably not all the pretenders have been removed. Conversely, at only 19% support for Obama, a large portion of those who entered an incorrect geography probably truly are Tea Party supporters.
Still, we should be able to identify demographics with large proportions of corrupted data from the proportion of respondents who misidentify their geography. Let's take a look below the fold.