There's a new example available of how different polls of the same category of voters on the same day and in the same place produce strikingly different results. Yesterday both CNN and Insider Advantage/Majority Opinion Research released polls of likely voters in the Florida GOP presidential primary, conducted over the same two-day period (November 25-26).
According to CNN, Rudy Giuliani has a huge lead in the Sunshine State, polling at 38%, with Mitt Romney at 17%, McCain and Thompson at 11%, and Mike Huckabee running fifth at 9%. According to Insider Advantage (per the Southern Political Report), the big story is that Huckabee's "surge" isn't limited to Iowa: he's running second in FL at 17%, trailing Rudy at 26%, but leading McCain at 13%, Romney at 12% and Thompson at 9%.
The CNN poll has a margin of error of 5.5%, while Insider Advantage's MoE is 3.5%. But somebody's just getting it wrong.
BTW, the CNN/Insider Advantage Sunshine Competition continues tonight, as the former sponsors the YouTube GOP presidential debate from St. Petersberg at 8:00 EST, and the latter conducts a snap poll of Florida Republicans on "who won."