Accelerated life test calculations using the method of maximum likelihood: an improvement over least squares

Accelerated life testing is a common way to determine the reliability of devices under use conditions. Typically, parts are aged at different (high) temperatures and the resulting failure times are used to predict the time to failure at use (low) temperature. For semiconductor devices, the failure times often follow a lognormal distribution. In this paper the author considers using the maximum likelihood method in the accelerated life test calculations and shows that it offers an improvement over the least squares method.