  Recently\cite{BQG}, it was shown that quantum effects of matter could be
identified with the conformal degree of freedom of the space-time metric.
Accordingly, one can introduce quantum effects either by making a scale
transformation (i.e. changing the metric), or by making a conformal
transformation (i.e. changing all physical quantities). These two ways are
investigated and compared. Also, it is argued that, the ultimate formulation of
such a quantum gravity theory should be in the framework of the scalar-tensor
theories.
