Planning accelerated life tests with random effects of test chambers |
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| Authors: | Kangwon Seo Rong Pan |
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| Affiliation: | 1. Department of Industrial and Manufacturing Systems Engineering, University of Missouri, Columbia, MO, USA;2. Department of Statistics, University of Missouri, Columbia, MO, USA;3. School of Computing, Informatics, and Decision Systems Engineering, Arizona State University, Tempe, AZ, USA |
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| Abstract: | In accelerated life tests (ALTs), test units are often tested in multiple test chambers along with different stress conditions. The nonhomogeneity of test chambers precludes the complete randomized experiment and may affect the life‐stress relationship of the test product. The chamber‐to‐chamber variation should be taken into account for ALT planning so as to obtain more accurate test results. In this paper, planning ALTs under a nested experimental design structure with random test chamber effects is studied. First, by a 2‐phase approach, we illustrate to what extent different test chamber assignments to stress conditions may impact the estimation of unknown parameters. Then, D‐optimal test plans with 2 test chambers are considered. To construct the optimal design, we establish the generalized linear mixed model for failure‐time data and apply a quasi‐likelihood method, where test chamber assignments, as well as other decision variables that are required for planning ALTs, are simultaneously determined. |
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| Keywords: | accelerated life tests D‐optimal design generalized linear mixed model nested experimental design random effects test chamber assignment |
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