Today's lesson is to never take a major media poll at face value. The latest CBS News poll has President Bush's job approval at a miniscule 35 percent -- that's 4-8 points lower than just about every other poll out there.

How does CBS News get such a low number? Real Clear Politics points out how:

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 country has a Republican president, Republican House and a Republican Senate -- and CBS estimates that the percentage of Republicans in the population is 23.8 percent.

Maybe in the future, CBS will simply poll DailyKos sitegoers and save the rest of us all the effort about taking them seriously.