IMT Institutional Repository: No conditions. Results ordered -Date Deposited. 2024-03-29T07:46:21ZEPrintshttp://eprints.imtlucca.it/images/logowhite.pnghttp://eprints.imtlucca.it/2011-10-31T13:38:27Z2012-01-18T08:01:11Zhttp://eprints.imtlucca.it/id/eprint/981This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/9812011-10-31T13:38:27ZAsymptotic results for a generalized Pólya urn with “multi-updating” and applications to clinical trialsIn this article, a new Pólya urn model is introduced and studied; in particular, a strong law of large numbers and two central limit theorems are proved. This urn generalizes a model studied in Berti et al. (2004), May et al. (2005), and in Crimaldi (2007), and it has natural applications in clinical trials. Indeed, the model includes both delayed and missing (or null) responses. Moreover, a connection with the conditional identity in distribution of Berti et al. (2004) is given.Irene Crimaldiirene.crimaldi@imtlucca.itFabrizio Leisen2011-10-31T11:30:01Z2011-11-03T13:19:36Zhttp://eprints.imtlucca.it/id/eprint/976This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/9762011-10-31T11:30:01ZConditionally identically distributed species sampling sequencesIn this paper the theory of species sampling sequences is linked to the theory of conditionally identically distributed sequences in order to enlarge the set of species sampling sequences which are mathematically tractable. The conditional identity in distribution (see Berti, Pratelli and Rigo (2004)) is a new type of dependence for random variables, which generalizes the well-known notion of exchangeability. In this paper a class of random sequences, called generalized species sampling sequences, is defined and a condition to have conditional identity in distribution is given. Moreover, two types of generalized species sampling sequence that are conditionally identically distributed are introduced and studied: the generalized Poisson-Dirichlet sequence and the generalized Ottawa sequence. Some examples are discussed. Federico BassettiIrene Crimaldiirene.crimaldi@imtlucca.itFabrizio Leisen