Characterizing Linear Birth and Death Processes
作者:
LorrieL. Hoffman,
期刊:
Journal of the American Statistical Association
(Taylor Available online 1992)
卷期:
Volume 87,
issue 420
页码: 1183-1187
ISSN:0162-1459
年代: 1992
DOI:10.1080/01621459.1992.10476276
出版商: Taylor & Francis Group
关键词: Markov process;Simulation;Steady state
数据来源: Taylor
摘要:
This research determined the manner of convergence of certain Markov processes to their steady state limiting distributions. This article looks at linear birth and death processes with birth rate at each state determined by the immigration constantaand the natural growth multiplierb;with death rate at each state determined by fixed execution constantcand the natural declination multiplierd. All parameters are nonnegative. There is a reflective barrier at state 0. It is shown that when the natural growth multiplier is less than the declination parameter a limiting distribution exists, that is, when the multiplier difference is negative. We define a modal indicator as the ratio of the sum of the death parameterscandddiminished by immigrationato the multiplier difference. It is shown that when the modal indicator is negative then the mode occurs at state 0. When the indicator is an integer then the process is bimodal with the mode at that integral value and at the next larger integer. When the indicator is not an integer then the mode occurs at the first integral value greater than the modal indicator. Additionally, bounds for the birth probabilities and the tail probabilities are derived. These equations are applied to an example in the area of computer performance analysis. The objective of studying the characteristics of the limiting distribution is to understand the difficulties involved when simulating these processes. The most extensively studied of these types of Markov processes is theM/M/1 process (Poisson arrivals to one server having exponential service times). This is a simple case of a linear birth and death process whereb=d= 0. Researchers have suggested speeding convergence by initializing the process in a state other than 0. This article reveals that zero is a good choice for theM/M/1 process, but it is not the best choice for the general linear birth and death process. Also, practitioners have devised empirical methods to decide when the number of iterationsNis sufficient to declare convergence. This article presents bounds on the tail probabilities in order to guide the selection ofNat the onset of simulation. The sense of the theorems proved below can be captured by these statements:1.The natural growth multiplierbmust be less than the declination parameterdto insure convergence.2.If the modal indicator is relatively large then intitializing the process in the modal state might be wise.3.Large values of the declination parameterdrelative to the growth multiplierbwill result in a better behaved process.
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