CHICAGO – President-elect Obama said Friday that the country is facing the greatest economic challenge in a lifetime and "we’re going to have to act swiftly to resolve it."

In his first news conference since winning the presidency Tuesday, Obama said Congress must pass an economic stimulus measure either before or just after he takes office in January. He also said unemployment benefits need to be extended. But he deferred to President Bush and his economic team on major decisions in the coming weeks. "The United States has only one government and one president at a time," Obama said.

1. Exit polls have a much larger intrinsic margin for error than regular polls.

2. Exit polls have consistently overstated the Democratic share of the vote.

3. Exit polls were particularly bad in this year’s primaries. 

4. Exit polls challenge the definition of a random sample.

5. Democrats may be more likely to participate in exit polls. 

6. Exit polls may have problems calibrating results from early voting.

7. Exit polls may also miss late voters. 

8. "Leaked" exit poll results may not be the genuine article.

9. A high-turnout election may make demographic weighting difficult. 

10. You’ll know the actual results soon enough anyway.