Gives numerical methods for complementing graphical techniques in performance of a goodness-of-fit test for Weibull distributed times to failure and provides an approximate method of obtaining confidence intervals for the parameters of the two-parameter Weibull distributions when estimating by maximum likelihood. It also gives a recommended method for obtaining lower confidence limits for the 10% fractiles of the lifetime and reliability function. Applies when a random sample of items is given a test of times to failure in order to estimate measures of reliability performance of the population from which these items were drawn.