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 - → ψ ( 3770 ) → D D ¯ transitions.