Lagrangian Probability Distributions
Lagrangian Probability Distributions
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DOI:
10.1007/0-8176-4477-6_2
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发表时间:
2005-12
期刊:
影响因子:
--
通讯作者:
P. Consul;F. Famoye
中科院分区:
文献类型:
--
作者:
P. Consul;F. Famoye
Discrete probability distributions are fitted to observed counts to find a pattern which may lead an investigator to see if some generating models can be set up for the process under study. As every phenomenon is of a multivariate nature, the task of finding the correct model becomes difficult. Practically all models for biological, psychological, social, agricultural, or natural processes are approximations. Thus, every model is a simplification of real life. Possibly, every observed pattern is the steady state of some stochastic process. As different researchers in the world are faced with observed counts in their respective fields and they try to find a specific pattern in their observations, their efforts lead them to the discovery of new and more complex probability distributions. A large number of discrete probability distributions are now available which are divided into various classes, families, and generalized univariate, bivariate, and multivariate discrete distributions. An extensive account of these discrete probability distributions and their important properties can be found in the well-known works by Balakrishnan and Nevzorov (2003), Johnson, Kotz, and Balakrishnan (1997), Johnson, Kotz, and Kemp (1992), Patil, et al.(1984), Patil and Joshi (1968), Johnson and Kotz (1969), Mardia (1970), Ord (1972), and many others. As this book was ready to go to press, we were informed that the book by Johnson, Kotz, and Kemp (1992) was under revision. Discrete Lagrangian probability distributions form a very large and important class which contains numerous families of probability distributions. These probability distributions are very useful because they occur quite frequently in various fields. Most of the research work on these distributions is available in journals only. The generalized Poisson distribution is one important model which has been discussed in detail by Consul (1989a). Johnson, Kotz, and Kemp (1992) have described some families of the class of Lagrangian probability distributions under different titles in five chapters of their book. The prime source of importance in the class of Lagrangian distributions is the Lagrange transformation z= ug (z), given by Lagrange (1736–1813) and used by him to express z as a power series in u and then to expand a function f (z) into a power series of u as described in Chapter 1. Otter (1949) was the first person who realized the importance of this transformation for the development of a multiplicative process. If g (z) is the pgf of the number of segments from any vertex in a rooted tree with a number of vertices, then the transformation z= ug (z) provides the pgf for the number of vertices in the rooted tree. Otter (1949) showed that the number of vertices after n segments in a tree can be interpreted as the number of members in the nth generation of a branching process and that it can be used in the study of epidemics, spread of