Thursday, November 03, 2005

CBS Skews Polling Data

In a CBS News opinion poll released Wednesday night, President Bush's approval rating was given as 35%. As Noel Sheppard of the NewsBusters blog shows, the methodology for the poll is skewed against Republicans. Don't yell at me folks, the math backs it up...

NewsBusters reported Wednesday evening, a new CBS News poll pegged President Bush's job approval rating at 35 percent. Tom Bevan of Real Clear Politics posted an analysis of this poll's methodology at his blog last evening (hat tip from a NewsBusters reader named "Jsemby"). What his figures show is that CBS polled 46% more Democrats in its weighted sample than Republicans:

New CBS News poll out tonight. Highlights:

· Bush job approval at all time low of 35%

· Bush favorable rating at 33%

· Right track 27%, wrong track 68%

· Congress job approval 34%

· Congressional Dem favorable rating 41%, Congressional Republican favorable rating 35%

Now for the numbers behind the numbers. Take a look at the composition of the respondents:

Total Respondents (Unweighted) = 936
Republicans = 259 (27.67%)
Democrats = 326 (34.83%)
Independents = 351 (37.5%)

Now look at the weighted sample:

Republicans: 223 (23.80%)
Democrats: 326 (34.79%)
Independents: 388 (41.4%)

The result is a 35% job approval for the president, which is roughly 4-8 points lower than the other polls out right now.

To put these numbers in proper perspective, according to the November 2004 exit polls, the nation's current party affiliation is 37 percent Democrats, 37 percent Republicans, and 26 percent Independents. As such, the polling agency involved in this result fell 36 percent short in sampling Republicans while over-sampling Independents by 59 percent.

This demonstrates what many statisticians have been saying about polls for years: If you are trying to ascertain a certain answer to a question, all you have to do is ask the right people.