Simultaneous Least Squares Treatment of Statistical and Systematic   Uncertainties
  We present a least squares method for estimating parameters from measurements of event yields in the presence of background and crossfeed. We adopt a unified approach to incorporating the statistical and systematic uncertainties on the experimental measurements input to the fit. We demonstrate this method with a fit for absolute hadronic D meson branching fractions, measured in e+e- -> \psi(3770) -> D\bar D$ transitions. 
Werner M. Sun