1,572 research outputs found
Bonetti, Luca
No full textVoce bio-bibliografica dedicata a Luca Bonetti in "Dizionario degli editori, tipografi, librai itineranti in Italia tra Quattrocento e Seicento" coordinato da Marco Santoro ; a cura di Rosa Marisa Borraccini, Giuseppe Lipari, Carmela Reale, Marco Santoro, Giancarlo Volpat
M statistic commands: interpoint distance distribution analysis.
No full textWe implement the commands mstat and mtest to perform inference based on the M statistic introduce by Bonetti and Pagano (2005=, a statistic that can be used to compare the interpoint distance distribution across groups of observations. The descriptions of the commands are accompanied by examples of applications with real and simulated data. We run the test on the Alt and Vach grave site dataset (Manjourides, 2009, Distance Based Methods for Space Time Modelling of the Health of Populations [PhD dissertation, Harvard School of Public Health]) and reject the null hypothesis, in contradiction to other published analyses. We also show how to adapt the techniques to discrete datasets with more than one unit in each location. Finally, we report an extensive application on breast cancer data in Massachusetts; in the application, we show the compatibility of the M commands with Pisati’s spmap package
Dove vanno i laici. Note sull’etica di Paolo Bonetti
No full textIl purgatorio dei laici, a book published by Paolo Bonetti in 2008, is an expression of the “restless laity” of its author. Composed of a series of meditations on the present stage of ethics, especially in its relations with the Catholic religion, that book appears to us today as a collection of “ethical fragments” from which we derive still useful reflections on the present stage of ethics in its relationships with bioethics and on the limits and paradoxes of a metaphysics and immutable "human nature". Reasonable claim to the authentic meaning of secularism and liberalism – keywords of Bonettian ethics –, this article was born from the attempt to trace a profile of the philosopher Bonetti before the challenges of contemporary world’s complexity
A new geometric approach to data analysis using the Minkowski polytope
No full textWe introduce a new approach to the analysis of random samples in Rd, based on a geometric transformation called the "Minkowski polytope" (MP). We describe how a theorem by Minkowski guarantees the existence and uniqueness of such a transformation, discuss its construction, and state a result about the almost sure convergence of a scaled version of the MP in R2. We show how the shape of the MP is sensitive to the presence of outliers and correlation in the sample. Finally, we use the MP to develop a new Monte Carlo test for spatial randomness over non-uniform populations, and illustrate its application on a well-known dataset of leukemia cases in the state of New York
Invited review of article: Jiang, Runchao; Lu, Wenbin; Song, Rui; Davidian, Marie (2017). On estimation of optimal treatment regimes for maximizing t-year survival probability. R. Stat. Soc. Ser. B. Stat. Methodol. 79 (2017), no. 4, 1165–1185.
No full textNo abstract availabl
A proposal for a two-step sampling design to oversample units responding to prescribed characteristics
No full textWe introduce a novel method to extract a sample from a finite population where units with desired characteristics are over-represented. The approach is both sequential and adaptive and allows, via suitable compositions of predictive and objective functions, to target specific subsets of the population. We consider the problem of estimation and conjecture the validity of a modified Horvitz–Thompson estimator capable to account for the imbalance induced by the targeting procedure. After discussing how to apply the method to the sampling of geographically distributed units, we investigate its potential via simulations.Online publication date: 19 Jan 201
Computing the exact distributions of some functions of the ordered multinomial counts: maximum, minimum, range and sums of order statistics
No full textStarting from seminal neglected work by Rappeport (1968), we revisit and expand on the exact algorithms to compute the distribution of the maximum, the minimum, the range, and the sum of the J largest order statistics of a multinomial random vector under the hypothesis of equiprobability. Our exact results can be useful in all those situations in which the multinomial distribution plays an important role, from goodness-of-fit tests to the study of Poisson processes, with applications spanning from biostatistics to finance. We describe the algorithms, motivate their use in statistical testing and illustrate two applications. We also provide the codes and ready-to-use tables of critical values
Interpoint distance distribution
No full textAbstract: The interpoint distance distribution (IDD) is the distribution of the random variable defined as the distance, or dissimilarity, between two i.i.d. random variables. Estimation and testing procedures are available, based on samples of i.i.d. observations for the one-sample and the two-sample problem. The IDD allows for a reduction in dimensionality and can be used to perform shape classification. It is also related to local quantities in spatial point processes
The Gini concentration test for survival data
No full textWe apply the well known Gini index to the measurement of concentration in survival times within groups of patients, and as a way to compare the distribution of survival times across groups of patients in clinical studies. In particular, we propose an estimator of a restricted version of the index from right censored data. We derive the asymptotic distribution of the resulting Gini statistic, and construct an estimator for its asymptotic variance. We use these results to propose a novel test for differences in the heterogeneity of survival distributions, which may suggest the presence of a differential treatment effect for some groups of patients. We focus in particular on traditional and generalized cure rate models, i.e., mixture models with a distribution of the lifetimes of the cured patients that is either degenerate at infinity or has a den- sity. Results from a simulation study suggest that the Gini index is useful in some situations, and that it should be considered together with existing tests (in particular, the Log-rank, Wilcoxon, and Gray-Tsiatis tests). Use of the test is illustrated on the classic data arising from the Eastern Cooperative Oncology Group melanoma clinical trial E1690
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