Some presidential trial heat polls ask about just the two major candidates, McCain and Obama, and then lump other responses in the dreaded "other" category.
Others ask the names. So, does it make a difference? Let's take a look at two polls, asked more or less at the same time.
The Pew Center asked:
"Now, suppose the 2008 presidential election were being held TODAY. If you had to choose between [see below], who would you vote for?" If other/unsure: "As of TODAY, do you LEAN more to [see below]?"
Only two names were provided in random rotation: McCain and Obama. The number of unsure/other is 12%.
The Research 2000 for news media client poll asked:
"If the election for president were held today, who would you vote for if the choices were between Barack Obama, the Democrat, John McCain, the Republican, Bob Barr, the Libertarian, or Ralph Nader, an independent?"
In this case we're presented the names of Barr and Nader (but not Cynthia McKinney, a Georgia girl running for the Greens). The other/unsure? 5%.
My point? Offering more alternatives may influence the numbers, especially if you are a minor , i.e., third-party, candidate. Can't get no public opinion love if you ain't even mentioned. Plus, if you don't mention other candidates, you artificially inflate the unsure votes.