Browsing by Author "de la Cruz, Rolando"

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    A Bayesian Mixture Cure Rate Model for Estimating Short-Term and Long-Term Recidivism
    (2023) de la Cruz, Rolando; Fuentes, Claudio; Padilla, Oslando
    Mixture cure rate models have been developed to analyze failure time data where a proportion never fails. For such data, standard survival models are usually not appropriate because they do not account for the possibility of non-failure. In this context, mixture cure rate models assume that the studied population is a mixture of susceptible subjects who may experience the event of interest and non-susceptible subjects that will never experience it. More specifically, mixture cure rate models are a class of survival time models in which the probability of an eventual failure is less than one and both the probability of eventual failure and the timing of failure depend (separately) on certain individual characteristics. In this paper, we propose a Bayesian approach to estimate parametric mixture cure rate models with covariates. The probability of eventual failure is estimated using a binary regression model, and the timing of failure is determined using a Weibull distribution. Inference for these models is attained using Markov Chain Monte Carlo methods under the proposed Bayesian framework. Finally, we illustrate the method using data on the return-to-prison time for a sample of prison releases of men convicted of sexual crimes against women in England and Wales and we use mixture cure rate models to investigate the risk factors for long-term and short-term survival of recidivism.
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    Medical and Surgical Treatments for Obesity Have Opposite Effects on Peptide YY and Appetite: A Prospective Study Controlled for Weight Loss
    (ENDOCRINE SOC, 2010) Valderas, Juan P.; Irribarra, Veronica; Boza, Camilo; de la Cruz, Rolando; Liberona, Yessica; Maria Acosta, Ana; Yolito, Macarena; Maiz, Alberto
    Context: The effects of medical and surgical treatments for obesity on peptide YY (PYY) levels, in patients with similar weight loss, remain unclear.
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    Modeling Recidivism through Bayesian Regression Models and Deep Neural Networks
    (2021) de la Cruz, Rolando; Padilla, Oslando; Valle, Mauricio A.; Ruz, Gonzalo A.
    This study aims to analyze and explore criminal recidivism with different modeling strategies: one based on an explanation of the phenomenon and another based on a prediction task. We compared three common statistical approaches for modeling recidivism: the logistic regression model, the Cox regression model, and the cure rate model. The parameters of these models were estimated from a Bayesian point of view. Additionally, for prediction purposes, we compared the Cox proportional model, a random survival forest, and a deep neural network. To conduct this study, we used a real dataset that corresponds to a cohort of individuals which consisted of men convicted of sexual crimes against women in 1973 in England and Wales. The results show that the logistic regression model tends to give more precise estimations of the probabilities of recidivism both globally and with the subgroups considered, but at the expense of running a model for each moment of the time that is of interest. The cure rate model with a relatively simple distribution, such as Weibull, provides acceptable estimations, and these tend to be better with longer follow-up periods. The Cox regression model can provide the most biased estimations with certain subgroups. The prediction results show the deep neural network's superiority compared to the Cox proportional model and the random survival forest.
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    On an extension of the von Mises distribution due to Batschelet
    (TAYLOR & FRANCIS LTD, 2011) Pewsey, Arthur; Shimizu, Kunio; de la Cruz, Rolando
    This paper considers the three-parameter family of symmetric unimodal circular distributions proposed by Batschelet in [1], an extension of the von Mises distribution containing distributional forms ranging from the highly leptokurtic to the very platykurtic. The family's fundamental properties are given, and likelihood-based techniques described which can be used to perform estimation and hypothesis testing. Analyses are presented of two data sets which illustrate how the family and three of its most direct competitors can be applied in the search for parsimonious models for circular data.