Several of the classical sequences in enumerative combinatorics have q-generalizations arising as generating functions for statistics defined on finite discrete structures. When q = 1, these generating functions reduce to the original sequences. When q = -1, on the other hand, one gets the difference in cardinalities between those members of a set having an even value for some statistic (on the set) with those members having an odd value. The current text provides a systematic study of the case q = -1, giving both algebraic and combinatorial treatments. For the latter, ...