We extend Klefsjo (1985) proof for the closure of the increasing failure rate average (IFRA) property under formation of parallel systems to k-out-of-n systems. We also show that any k-out-of-n system with 1≤k<n independent and identically distributed components has the new better than average failure rate (NBAFR) property. This is true for k=1 even if the underlying components are not identical.
Ahmed, A., & Abouammoh, A. (1988). On Closure under Formation of Coherent Systems. The Egyptian Statistical Journal, 32(1), 57-61. doi: 10.21608/esju.1988.316550
MLA
A. N. Ahmed; A. M. Abouammoh. "On Closure under Formation of Coherent Systems", The Egyptian Statistical Journal, 32, 1, 1988, 57-61. doi: 10.21608/esju.1988.316550
HARVARD
Ahmed, A., Abouammoh, A. (1988). 'On Closure under Formation of Coherent Systems', The Egyptian Statistical Journal, 32(1), pp. 57-61. doi: 10.21608/esju.1988.316550
VANCOUVER
Ahmed, A., Abouammoh, A. On Closure under Formation of Coherent Systems. The Egyptian Statistical Journal, 1988; 32(1): 57-61. doi: 10.21608/esju.1988.316550
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