  We review our recent studies on the dynamical correlations in MC simulations
from the view point of the statistical dependence. Attentions are paid to the
reduction of the statistical degrees of freedom for correlated data. Possible
biases on several cumulants, such as the susceptibility and the Binder number
due to finite MC length are discussed. A new method for calculating the
equilibrium relaxation time from the analysis of the statistical dependence is
presented. We apply it to the critical dynamics of the Ising model to estimate
the dynamical critical exponent accurately.
