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We prove that the generalized Poisson distribution GP(theta, eta) (eta > or = 0) is a mixture of Poisson distributions; this is a new property for a distribution which is the topic of the book by Consul (1989). Because we find that the fits to count data of the generalized Poisson and negative binomial distributions are often similar, to understand their(More)
To evaluate clinical and molecular predictors of the risk of mortality in people with neurofibromatosis 2 (NF2), we analyzed the mortality experience of 368 patients from 261 families in the United Kingdom NF2 registry, using the Cox proportional-hazards model and the jackknife method. Age at diagnosis, intracranial meningiomas, and type of treatment center(More)
The extremal dependence behavior of t copulas is examined and their extreme value limiting copulas, called the t-EV copulas, are derived explicitly using the tail dependence functions. As two special cases, the Hüsler-Reiss and the Marshall-Olkin distributions emerge as limits of the t-EV copula as the degrees of freedom go to infinity and zero(More)
Tail dependence and conditional tail dependence functions describe, respectively, the tail probabilities and conditional tail probabilities of a copula at various relative scales. The properties as well as the interplay of these two functions are established based upon their homogeneous structures. The extremal dependence of a copula, as described by its(More)
High-dimensional contingency tables tend to be sparse, and standard goodness-of-fit statistics such as X2 cannot be used without pooling categories. As an improvement on arbitrary pooling, for goodness of fit of large 2n contingency tables, we propose classes of quadratic form statistics based on the residuals of margins or multivariate moments up to order(More)
BACKGROUND Four sets of clinical diagnostic criteria for neurofibromatosis 2 (NF2) have been developed by groups of expert clinicians, but sensitivity has never been formally assessed. The sets of criteria differ for people without bilateral vestibular schwannomas, which are pathognomonic for NF2. OBJECTIVE To empirically evaluate the four existing sets(More)
PURPOSE Four sets of clinical diagnostic criteria have been proposed for neurofibromatosis 2, but all have low sensitivity at the time of initial clinical assessment for the disease among patients with a negative family history who do not present with bilateral vestibular schwannomas. We have empirically developed and tested an improved set of diagnostic(More)
The network algorithm of Mehta and Patel [ 1986] m currently the best general algorithm for computing exact probabilities in r x c contingency tables with fixed marginals. Given here are some improvements to the network algorithm which speed Its computational performance; and thus increases the size of problems which can be handled, The new code also(More)