Efficiency and Accuracy of Accelerated Life Test Plans
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Minitab evaluates the efficiency of each plan and ranks them in order. Efficiency is measured in terms of the variance of the parameter you want to estimate. It is possible, however, for a highly efficient test plan (one with small variance) to produce results that are not accurate. In particular, the results of an accelerated life test are based on obtaining enough failures at each stress level to accurately estimate the parameter of interest. To obtain accurate parameter estimates, a common rule of thumb is that the expected number of failures at each of the test stresses should be at least four or five.

By default, Minitab displays three different test plans.