Abstract
The coherent systems are basic concepts in reliability theory and survival analysis. They contain as particular cases the popular series, parallel and k-out-of-n systems (order statistics). Many results have been obtained for them by assuming that the component lifetimes are independent. In many practical cases, this assumption is unrealistic. In this paper, we study them by assuming a time-transformed exponential model for the joint distribution of the component lifetimes. This model is equivalent to the frailty model which assumes that they are conditionally independent given a common risk parameter (which represents the common environment risk). Under this model, we obtain explicit expressions for the system reliability function and comparison results for the main stochastic orders. We obtain both expressions from minimal path sets and those from minimal survival signatures. Some aging classes and the system residual lifetime (under different assumptions) are studied as well.
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References
Barlow RE, Mendel MB (1992) De Finetti-type representations for life distributions. J Am Stat Assoc 87:1116–1122
Barlow RE, Proschan F (1975) Statistical theory of reliability and life testing. International Series in Decision Processes, Holt, Rinehart and Winston Inc, New York
Bassan B, Spizzichino F (2005) Relations among univariate aging, bivariate aging and dependence for exchangeable lifetimes. J Multivar Anal 93:313–339
Caramellino L, Spizzichino F (1994) Dependence and aging properties of lifetimes with Schur-constant survival functions. Prob Eng Inf Sci 8:103–111
Caramellino L, Spizzichino F (1996) WBF property and stochastical monotonicity of the Markov process associated to Schur-constant survival functions. J Multivar Anal 56:153–163
Coolen FPA, Coolen-Maturi T (2012) On generalizing the signature to systems with multiple types of components. In: Zamojski W et al (eds) Complex systems and dependability. Springer, Berlin, pp 115–130
De Michele C, Salvadori G, Canossi M, Petaccia A, Rosso R (2005) Bivariate statistical approach to check adequacy of dam spillway. J Hydrol Eng 10:50–57
Duchateau L, Janssen P (2008) The frailty model. Springer, New York
Eryilmaz S, Coolen FPA, Coolen-Maturi T (2018) Mean residual life of coherent systems consisting of multiple types of dependent components. Naval Res Logist 65:86–97
Eryilmaz S, Tekin M (2019) Reliability evaluation of a system under a mixed shock model. J Comput Appl Math 352:255–261
Genest C, Favre AC (2007) Everything you always wanted to know about copula modeling but were afraid to ask. J Hydrol Eng 12:347–368
Hougaard P (2000) Analysis of multivariate survival data. Springer, New York
Kozlova M, Salminen P (2004) Diffusion local time storage. Stoch Proc Appl 114:211–229
Mulero J, Pellerey F (2010) Bivariate aging properties under Archimedean dependence structures. Commun Stat Theory Methods 39:3108–3121
Mulero J, Pellerey F, Rodríguez-Griñolo R (2010a) Stochastic comparisons for time transformed exponential models. Insur Math Econ 46:328–333
Mulero J, Pellerey F, Rodríguez-Griñolo R (2010b) Negative aging and stochastic comparisons of residual lifetimes in multivariate frailty models. J Stat Plan Inference 140:1594–1600
Müller A, Scarsini M (2005) Archimedean copulae and positive dependence. J Multivar Anal 93:434–445
Navarro J (2018a) Stochastic comparisons of coherent systems. Metrika 81:465–482
Navarro J (2018b) Distribution-free comparisons of residual lifetimes of coherent systems based on copula properties. Stat Papers 59:781–800
Navarro J, Pellerey F, Longobardi M (2017) Comparison results for inactivity times of \(k\)-out-of-\(n\) and general coherent systems with dependent components. Test 26:822–846
Nelsen RB (2006) An introduction to copulas, 2nd edn. Springer, New York
Ozkut M, Eryilmaz S (2019) Reliability analysis under Marshall–Olkin run shock model. J Comput Appl Math 349:52–59
Pellerey F, Zalzadeh S (2014) On preservation of ageing under minimum for dependent random lifetimes. Hacet J Math Stat 43:873–884
Ta BQ, Wan CP (2017) Some properties of bivariate Schur-constant distributions. Stat Prob Lett 124:69–76
Tuncel A, Eryilmaz S (2018) System reliability under \(\delta \)-shock model. Commun Stat Theory Methods 47:4872–4880
Shaked M, Shanthikumar JG (2007) Stochastic orders. Springer, New York
Wienke A (2011) Frailty models in survival analysis. Chapman & Hall/CRC, Boca Raton
Acknowledgements
We would like to thank the anonymous associated editor and reviewers for several helpful suggestions. In particular, we want to mention that Sects. 4 and 6 and Remark 1 are due to these suggestions. JN and JM acknowledge the support received from Ministerio de Economía, Industria y Competitividad of Spain under grant MTM2016-79943-P (AEI/ FEDER, UE). JM also acknowledges the support received from the Conselleria d’Educació, Investigació, Cultura i Esport (Generalitat de la Comunitat Valenciana) under grant GV/2017/015.
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Navarro, J., Mulero, J. Comparisons of coherent systems under the time-transformed exponential model. TEST 29, 255–281 (2020). https://doi.org/10.1007/s11749-019-00656-4
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DOI: https://doi.org/10.1007/s11749-019-00656-4