Rounding error? More likely stupidity.
“Looking inside the numbers, Obama continues to lead Romney among key parts of his political base, including African Americans (94 percent to 0 percent), Latinos (by a 2-to-1 margin), voters under 35-years-old (52 percent to 41 percent) and women (51 percent to 41 percent).”
http://firstread.nbcnews.com/_news/2012/08/21/13399788-nbcwsj-poll-heading-into-conventions-obama-has-four-point-lead?lite
Wonder what happened to the missing 6 percent of African Americans?
To say nothing of the missing young and female voters.