Tuesday, October 17, 2006

Depends on the pond you fish (or, 58-42 should raise a flag) 

Polling is all the rage, and a real problem with polls is getting the information you need to determine how realiable it is. DFLers are hooting it up over the new Minnesota Poll (via the StarTribune) which has Patty Wetterling up 48-40 over Michele Bachmann in the Sixth Congressional District Race. Jeff Kouba places the poll in perspective and argues the number for Wetterling is too high. Larry Schumacher notes:
Reporter Eric Black mentions in his story that the respondents to the poll broke down pretty evenly between Republicans, Democrats and Independents. Now, that's not the 6th Congressional District that I know, at least not exactly. Historically the district has broken down about 40 percent Republican, 30 percent Democrat and 30 percent Independent this decade.
Well, through some investigation I have found the tabs that Larry and Jeff could use.
Republican 30%
Democrat 34%
Independent 23%
Other/None/DK/Refused 13%
When they pushed the Independent and other voters to identify leanings, you get 9% more Republican and 16% more Democrat. Now, as my friends at the SCSU Survey will remind me, party ID is meaningless, just a point-in-time identification. But in a district that voted 57-42 for George Bush in 2004, how likely is it that the district in two years moves that much? Ergo, the 33-33-33 split Jeff thought when he studied the race is actually 30-34-36. And when Larry wonders "are Republicans being undersampled or is there a shift going on that is chipping away at the Republican advantage in this district," I think you have to say at least some of it is undersampling. But read on, because I'm saving the best for last.

Some other information from the data I have:
The Minnesota poll is an outlier. Whether or not they did this intentionally is not the issue -- a poll that was so overweighted with female voters in a race with a notable gender gap should have raised a flag. They fished a pond that had too many of one kind of fish.