The poll was conducted by landline and cellphone June 28-July 9, 2012 among 2,973 adults, including 2,373 registered voters. The samples were weighted to account for demographic composition, with sampling errors taking into account the effect of weighting.
2,373 registered adults, the rest, 620 not registered. Almost 20%.
Certain parts of the poll used all the sample and other parts used only the registered sample. They tell you which in the details.
The presidential match-up used only the registered sample.