Voter Suppression and Political Polls

By CHARLES M. BLOW, NYT

Polls are the best way to find out who plans to vote and for whom they plan to vote. But polls are imperfect. They ask questions of a sampling of people - often about a thousand - and use those answers to draw conclusions about the public at large.

This year there is a new wrinkle, one that complicates the picture and could throw some of the polling off: the effects of newly enacted restrictive voting laws.

Take, for instance, the results of a New York Times/CBS News/Quinnipiac poll released Wednesday. "Likely voters" were polled in the swing states of Florida, Ohio and Pennsylvania, and President Obama led Mitt Romney in each state - by 6 points in Ohio and Florida and by 11 points in Pennsylvania. President Obama carried all three states in the last election and needs them in this one. Encouraging for him, right?

But let's dig in a bit and look at some of the variables that could weigh on those results.

(More here.)