The suggestion of the range -100 to +100 (allowing "yes" or "no")
is equivalent to 0 to 100. In fact every range is
EQUIVALENT to every other. You could use 754-to-982. It would be
weird, but exactly the same winners (and same
ordering of the 1st, 2nd, 3rd... place winners)
would happen as with 0-to-99,
assuming the voters rescaled their votes to the new range.
The only reason I suggest 0-to-99 is we have to pick some
concrete choice and it seems simpler. Some voters are confused by
negative numbers and it is best to minimize confusion.
(Although I admit I kind of enjoy the idea of a lot of
candidates getting a NEGATIVE total vote... it probably would not increase
the system's popularity among politicians. Imagine Kerry beating Bush
by a score of -57 to -63...)