*nonrepresentative*

adj. 1. Not standing for something else. Opposite of representative.
Syn. -- unsymbolic. [ WordNet 1.5 ]

2. Not giving a true representation of the characteristics of a group; -- of a sample or subgroup of a group; as, the weather we had in the summer of 1996 gave a nonrepresentative view of our normal weather.
Syn. -- biased, unrepresentative. [ PJC ]