The Modi ed Sudden Death Test: Planning Life Tests with a Limited Number of Test Positions

We present modi ed sudden death test (MSDT) plans to address the problem of limited testing positions in life tests. A single MSDT involves testing k specimens simultaneously until the rth failure. The traditional sudden death test (SDT) is a special case when r = 1. The complete MSDT plan consists of g single MSDTs run in sequence. When r > 1, there can be up to r 1 idle test positions at any time. We propose testing \standby" specimens in the idle positions and use simulation to gauge the improvement over the basic MSDT plan. We evaluate test plans with respect to the asymptotic variance of maximum likelihood estimators of quantities of interest, total experiment duration and sample size. In contrast to traditional experimental plans, shorter total testing time and smaller sample sizes are possible under MSDT plans.