  Estimations of physical parameters using data usually involve non-uniform
experimental efficiencies. In this article, a method of maximum likelihood fit
is introduced using the efficiency as a weight, while the probability
distribution function is kept unaffected by the efficiency. A brief proof and
pseudo-experiment studies suggest that this method gives unbiased estimation of
parameters. For cases where the probability distribution function can be
normalized analytically, this method significant reduces the usage of computing
resources.
