Impact of Forecast Uncertainty on Feeder-Cable Sizing

Abstract

This paper estimates the forecast error distribution for outside plant using data from the central office forecast measurement plan. We then determine the impact of the forecast errors on feeder-cable sizing by using this distribution to estimate the conditional distribution of engineered cable size with respect to optimum cable size. The marginal distribution of optimum cable size is estimated from a growth rate distribution which in turn is estimated from cable shipment data. We then use the resulting joint distribution to weight the percentage cost penalty of each possible combination of optimum and forecast size. The impact analysis is done separately for each gauge. By weighting by the million conductor feet of each gauge shipped, we then obtain an estimate of overall sizing-error cost penalty. The resulting penalty estimate is about 0.5 percent of the annual feeder-cable-construction program.