Poll Averages Have No History of Consistent Partisan Bias - NYTimes.com

Information Irresponsibility 101: If you don’t like the data, claim bias in its collection.

Presidential elections are high-stakes affairs. So perhaps it is no surprise that when supporters of one candidate do not like the message they are hearing from the polls they tend to blame the messenger.

In 2004, Democratic Web sites were convinced that the polls were biased toward George W. Bush, asserting that they showed an implausible gain in the number of voters identifying as Republicans. But in fact, the polls were very near the actual result. Mr. Bush defeated John Kerry by 2.5 percentage points, close to (in fact just slightly better than) the 1- or 2-point lead that he had on average in the final polls. Exit polls that year found an equal number of voters describing themselves as Democrats and Republicans, also close to what the polls had predicted.

Since President Obama gained ground in the polls after the Democrats’ convention, it has been the Republicans’ turn to make the same accusations.

Poll Averages Have No History of Consistent Partisan Bias - NYTimes.com