87,101 research outputs found
A comparative study on multiple comparisons procedures
No full textA comparative study on multiple comparisons procedures is performed and described, taking into account a new method to evaluate the performances af multiple comparisons procedures proposed by the author
Nonparametric inference via permutation tests for Cub models
No full textAbstract In statistical surveys, respondents are often asked to express evaluations on several topics. The rating problem can be often faced in many fields. A new approach is represented by a class of mixture models with covariates (CUB models).
Together with parametric inference, a permutation solution to test for covariates effects, when an univariate response is considered, has been discussed in [1], where the preference for a permutation test as compared to asymptotic ones when the sample size is moderate or even small has been justified through a simulation study. We propose an extension of this nonparametric inference to deal with the multivariate case. The method is applied to a real data set
Permutation inference for a class of mixture models
No full textIn statistical surveys, people are often asked to express evaluations on several topics or to make an ordered arrangement in a list of objects (items, services, sentences, etc.); thus, the analysis of ratings and rankings is receiving a growing interest in many fields. In this framework, we develop a testing procedure for a class of mixture models with covariates (defined as cub models), proposed by Piccolo (2003) and D'Elia and Piccolo (2005) and generally developed in a parametric context. Instead, we propose a nonparametric solution to perform inference on cub models, specifically on the coefficients of the covariates. A simulation study proves that this approach is more appropriate in some specific data settings, mostly for small sample sizes
Non-parametric two-stage active control testing method for non-inferiority tests
No full textOne of statistics’ most important application fields in medicine is the comparison of different populations, and in particular the evaluation of the differences between the effects of two medical treatments. In this work we deal with a specific issue directly related to this application field, i.e. the non-inferiority test. Placebocontrolled trials are in fact ideal to evaluate medical treatment effectiveness, but they are ethically justified only if no standard treatment exists. In these cases activecontrolled trials are generally more appropriate, and in particular the non-inferiority trial. The Two-Stage Active Control Testing (TACT) method is suitable for evaluating differences between a new treatment and the control. Here we propose a permutation version of this technique that may be used when usual distributional assumptions do not hold
Nonparametric methods for the comparison of two techniques of surgical operation to repair abdominal aortic aneurysms
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Advances in CUB models with application to the evaluation of natural parks in the Dolomites
No full textThe Cub model and the permutation test on covariates of this model were applied to evaluate the customer satisfaction of tourists who visited the natural parks of the Dolomites on the north of Italy
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