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Recursos bibliográficos en papel y digitales -
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» Resultado: 3 registros
| Registro 1 de 3 | |
| Autor: | Mandel, Micha - Betensky, Rebecca A. - |
| Título: | Testing goodness of fit of a uniform truncation model |
| Fuente: | Biometrics. v.63, n.2. International Biometric Society |
| Páginas: | pp. 405-412 |
| Año: | jun. 2007 |
| Resumen: | Several goodness-of-fit tests of a lifetime distribution have been suggested in the literature; many take into account censoring and/or truncation of event times. In some contexts, a goodness-of-fit test for the truncation distribution is of interest. In particular, better estimates of the lifetime distribution can be obtained when knowledge of the truncation law is exploited. In cross-sectional sampling, for example, there are theoretical justifications for the assumption of a uniform truncation distribution, and several studies have used it to improve the efficiency of their survival estimates. The duality of lifetime and truncation in the absence of censoring enables methods for testing goodness of fit of the lifetime distribution to be used for testing goodness of fit of the truncation distribution. However, under random censoring, this duality does not hold and different tests are required. In this article, we introduce several goodness-of-fit tests for the truncation distribution and investigate their performance in the presence of censored event times using simulation. We demonstrate the use of our tests on two data sets. |
| Solicitar por: | HEMEROTECA B + datos de Fuente |
| Registro 2 de 3 | |
| Autor: | Betensky, Rebecca A. - Christian, Caprice K. - Gustafson, Michael L. - Daley, Jennifer - Zinner, Michael J. |
| Título: | Hospital volume versus outcome: An unusual example of bivariate association |
| Fuente: | Biometrics. v.62, n.2. International Biometric Society |
| Páginas: | pp. 598-604 |
| Año: | jun. 2006 |
| Resumen: | The Leapfrog Group, a consortium of more than 100 large employers, purchasing coalitions, and states that collectively provide health insurance to more than 33 million people, convened in 2000 with the goal of using market forces to improve the quality of healthcare. The resulting Leapfrog initiative suggested selective referral of complex procedures to high-volume hospitals and set volume thresholds for five procedures. This was based on the hypothesis that low-volume hospitals have higher mortality, which can be viewed in simplified statistical terms as the hypothesis that the binomial p is a decreasing function of n. The analysis of the correlation between hospitals’ standardized mortality ratios (SMR, i.e., the ratio of observed to expected deaths) and hospitals’ procedural volumes is revealing about the volume/mortality hypothesis. This presents an unusual pedagogic example in which the detection of correlation in the presence of nonlinear dependence is of primary interest, and thus the Pearson correlation is ideally suited. The frequently preferred nonparametric measures of bivariate association are inappropriate as they are unable to discriminate between correlation and dependence. |
| Solicitar por: | HEMEROTECA B + datos de Fuente |
| Registro 3 de 3 | |
| Autor: | Cai, Tianxi - Betensky, Rebecca A. - |
| Título: | Hazard regression for interval-censored data with penalized spline |
| Fuente: | Biometrics. v.59, n.3. International Biometric Society |
| Páginas: | pp. 570-579 |
| Año: | sep. 2003 |
| Resumen: | This article introduces a new approach for estimating the hazard function for possibly interval- and right-censored survival data. We weakly parameterize the log-hazard function with a piecewise-linear spline and provide a smoothed estimate of the hazard function by maximizing the penalized likelihood through a mixed model-based approach. We also provide a method to estimate the amount of smoothing from the data. We illustrate our approach with two well-known interval-censored data sets. Extensive numerical studies are conducted to evaluate the efficacy of the new procedure. |
| Solicitar por: | HEMEROTECA B + datos de Fuente |
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