Comparison of weighted and unweighted histograms
  Two modifications of the chi square test for comparing usual(unweighted) and weighted histograms and two weighted histograms are proposed. Numerical examples illustrate an application of the tests for the histograms with different statistics of events. Proposed tests can be used for the comparison of experimental data histograms against simulated data histograms and two simulated data histograms. 
N.D. Gagunashvili