  We propose an indistinguishability measure for assessment of ansatz
wavefunctions with numerically determined wavefunctions. The measure
efficiently compares all correlation functions of two states and can therefore
be used to distinguish phases by defining correlator classes for ansatz
wavefunctions. It also allows identification of quantum critical points. We
demonstrate the approach for the transverse Ising model, using the matrix
product state formalism with the time evolving block decimation algorithm.
