Statistical Evaluation of Learning Factor in Reliability Studies
A mathematical formulation is developed which allows the statistical evaluation of certain features of the probability distribution of the ratio between two random variables as in the determination of learning factors. This evaluation is of the mode, an s-confidence band for the ratio, and the effect of sample size.
Confidence Intervals for the Ratio of Two Poisson Means and Poisson Predictor Intervals
Easy-to-use charts are presented for confidence intervals for the ratio of two Poisson mean occurrence rates and for predictor intervals for the future value of a Poisson random variable, given a previously observed value. The use of the charts is illustrated and their theoretical basis is given.
Determination and Analysis of Data for Reliability Studies
Methods for transmission and distribution system reliability analysis currently being developed and used require that the expected values of component outage rates and outage durations be known. The paper describes how the required component parameters can be estimated from field data. Also described are methods of placing confidence limits on the parameters estimated. The methods presented were developed through a study of six years of field records provided by a utility company. Sample expected outage rates and outage durations for various components such as transmission lines, substation transformers, and circuit breakers are presented. Also presented are data which tend to confirm the distributional assumptions made in system reliability analysis methods.