For alot of "regular people" (approx a third of the lower 2 income bracket polls) that make somewhere between 0 and 50,000. I think an extra poll should have been made. Really the difference between part time/minimum wage (whatever that may be in your area), and a 40hr a week @ $30/hr...
under $20k (part time, unemployed, student, etc)
or something like that. But it looks like the majority make more then $50k (which is a bit surprising to me) so guess it doesn't really matter.