Evaluation of Systematic Uncertainties

In this chapter all areas of possible systematic uncertainty are investigated. In each case the uncertainty is quantified so that it can be included in the final results. For the TGC fit a systematic error is calculated for each bin of the SDM elements and $\cos\theta_{\rm W}$ distribution, and these are then included in the $\chi ^{2}$ fit as detailed in chapter 7. These uncertainties are calculated by comparing the SDM elements and $\cos\theta_{\rm W}$ observables. For each area of systematic uncertainty detailed in this chapter the absolute difference between the observables is taken as the systematic error.

An error on the polarised cross-section fractions is calculated for each area of uncertainty. These are combined with the statistical error in quadrature to give the overall uncertainty on each of the measured values from the 189 GeV data.