The number of independents is a function of how we present the results, not the methodology per se. We ask our respondents to provide party id, then follow up with independents to ask how they lean. As I’m sure you know, most self-identified leaners exhibit behavior that in many cases is actually more similar to strong party identifiers — a tendency that is fairly evident in the cross tabs of this and other polls. As a result, we isolate what people tend to think of as “true independents” and group the leaners with their more likely tendencies in these breakdowns. There is of course bound to be some error in this, but we think that it’s a lot less than if one just keeps the leaners in the category. If you want to test this yourself, we will of course be posting the original and complete dataset later in the week, so you can conduct your own analysis. (For now, you can extrapolate the breakdown of the 7-point scale in the partial crosstabs posted at the Trib site.)
I appreciate the clarification, and I look forward to seeing the complete dataset. Henson also sent me this detailed explanation of the methodology random matched sampling method, which was written by Doug Rivers. I need to spend a little time with it, but there it is for you. You can also listen to Henson’s colleague Daron Shaw explain the methodology.
Henson also noted that he has only done this style of poll since July of 2008 – you can see all of those results here. I was thinking of Lyceum polls from earlier than that, which Henson did with Shaw, but which were phone polls. The results of interest to me from 2008 are the July (McCain 43, Obama 33) and October (McCain 49, Obama 38) polls, which were a pretty accurate reflection of the final spread.
I think that addresses all of my questions. My thanks to James Henson for the information.
UPDATE: On a tangential note, Phillip Martin has put together a handy dandy chart showing all public polling data on the Perry/White race since February. If you take the average, Perry has a 47-40 lead.
UPDATE: Here’s Dr. Murray’s take on the poll.