Estimating agreement coefficients from sample survey data

We present a generalized estimating equations approach for estimating the concordance correlation coefficient and the kappa coefficient from sample survey data. The estimates and their accompanying standard error need to correctly account for the sampling design. Weighted measures of the concordance correlation coefficient and the kappa coefficient, along with the variance of these measures accounting for the sampling design, are presented. We use the Taylor series linearization method and the jackknife procedure for estimating the standard errors of the resulting parameter estimates. Body measurement and oral health data from the Third National Health and Nutrition Examination Survey are used to illustrate this methodology.Keywords: Generalized estimating equations, Sample weighting, Concordance correlation coefficient, Stratification, Taylor series linearization, Kappa coefficient, Jackknife estimator, ClusteringKeywords: Generalized estimating equations, Sample weighting, Concordance correlation coefficient, Stratification, Taylor series linearization, Kappa coefficient, Jackknife estimator, Clusterin

Adaptive Mantel Test for AssociationTesting in Imaging Genetics Data

Mantel's test (MT) for association is conducted by testing the linear relationship of similarity of all pairs of subjects between two observational domains. Motivated by applications to neuroimaging and genetics data, and following the succes of shrinkage and kernel methods for prediction with high-dimensional data, we here introduce the adaptive Mantel test as an extension of the MT. By utilizing kernels and penalized similarity measures, the adaptive Mantel test is able to achieve higher statistical power relative to the classical MT in many settings. Furthermore, the adaptive Mantel test is designed to simultaneously test over multiple similarity measures such that the correct type I error rate under the null hypothesis is maintained without the need to directly adjust the significance threshold for multiple testing. The performance of the adaptive Mantel test is evaluated on simulated data, and is used to investigate associations between genetics markers related to Alzheimer's Disease and heatlhy brain physiology with data from a working memory study of 350 college students from Beijing Normal University

Approximate Bayesian inference in semiparametric copula models

We describe a simple method for making inference on a functional of a multivariate distribution. The method is based on a copula representation of the multivariate distribution and it is based on the properties of an Approximate Bayesian Monte Carlo algorithm, where the proposed values of the functional of interest are weighed in terms of their empirical likelihood. This method is particularly useful when the "true" likelihood function associated with the working model is too costly to evaluate or when the working model is only partially specified.Comment: 27 pages, 18 figure

Statistics for Copula-based Measures of Multivariate Association - Theory and Applications to Financial Data

Concepts of association or dependence play a central role when considering multiple random sources in statistical models as they describe the relationship between two or more random variables. In particular, the concept of copulas has proven to be useful in many fields of application and research. Copulas split the multivariate distribution function of a random vector into the univariate marginal distribution functions and the dependence structure represented by the copula. This dissertation addresses the modeling, the estimation and the statistical inference of multivariate versions of copula-based measures of association such as Spearman's rho. Special focus is put on the analysis of the statistical properties of related nonparametric estimators as well as the derivation of statistical hypothesis tests. The latter may be used to verify specific modeling assumptions such as, for example, equal pairwise rank correlation. Further, statistical tests are developed to identify significant changes of association over time. The theoretical results are illustrated with applications to financial data

Comparação dos dinamômetros Camry e Jamar para seu uso em adultos colombianos saudáveis

Objective: Hand grip strength can provide an objective index of general upper strength, but hand dynamometer has not been validated for use in Colombia. The objective was to determine the interchangeability between Camry electronic and Jamar hydraulic hand grip dynamometers in a population found on the campus of the Universidad Nacional de Colombia and the elderly living in a community. Methods: This was a cross-sectional concordance study on 18-88-year-old males and females. Data regarding their demographics, health, and anthropometric variables were collected/measured and the Lin concordance correlation coefficient (CCC) along with Bland-Altman plots were used for evaluating concordance regarding both devices. Results: One hundred and thirty-three subjects participated in this study (average age 47±20.74 years-old). Right hand (RH) grip strength was 32.15 ± 9.96 kg with the Jamar dynamometer and 29.95 ± 9.18 kg with the Camry device. It is worth highlighting that the Jamar instrument presents higher values than the Camry instrument (p <0.05). CCC was only significant at the population level and for the 40-59-year-old age group. Bland-Altman plots had narrow limits of agreement. Conclusion: We concluded that the Camry dynamometer could replace the Jamar dynamometer in the 40-59-year-old age group; furthermore, it would be appropriate for medical use in patient monitoring or follow-up due to the close values observed.Objetivo. La fuerza de agarre de la mano puede proporcionar un índice objetivo de la fuerza de los miembros superiores, pero no se dispone de un dinamómetro de mano validado para su uso en Colombia. El objetivo fue determinar la intercambiabilidad entre los dinamómetros hidráulicos Jamar y el dinamómetro electrónico Camry en una población que se encuentra en el campus de la Universidad Nacional de Colombia y personas mayores que viven en una comunidad. Métodos. Estudio transversal de concordancia realizado en hombres y mujeres de 18 a 88 años de edad. Se recolectó información sobre variables demográficas, de salud y antropométricas. El coeficiente de correlación de concordancia de Lin (CCC) y los gráficos de Bland-Altman se utilizaron para evaluar la concordancia entre ambos dispositivos. Resultados. Participaron 133 sujetos (edad promedio de 47 ± 20,74 años). La fuerza de agarre de la mano derecha fue de 32,15 ± 9,96 kg con el dinamómetro Jamar y de 29,95 ± 9,18 kg con el dispositivo Camry, destacando que el equipo Jamar presenta valores superiores al Jamar (p<0.05). La CCC solo fue significativa a nivel de la población y para el grupo de edad de 40 a 59 años. Los gráficos Bland-Altman presentaron límites de acuerdo estrechos. Conclusión. Concluimos que el dinamómetro Camry podría reemplazar el dinamómetro Jamar en el grupo de edad de 40-59 años; además, sería apropiado para uso médico en el monitoreo o seguimiento de pacientes debido a los valores cercanos observados.Objetivo. A força de agarramento manual pode fornecer um índice objetivo da força dos membros superiores, mas um dinamômetro manual validado não está disponível para uso na Colômbia. O objetivo foi comparar os dinamômetros hidráulicos Jamar com o dinamômetro eletrônico Camry e establecer a possibilidade de equivalência no seu uso, na população do campus da Universidad Nacional de Colombia e em idosos que moram em uma comunidade.Métodos. estudo de concordância transversal realizado em homens e mulheres de 18 a 88 anos de idade. Foram coletadas informações sobre variáveis demográficas, sanitárias e antropométricas. O coeficiente de correlação de concordância deLin (CCC) e os gráficos de Bland-Altman foram utilizados paraavaliar a de equivalência entre os dois dispositivos.Resultados. 133 sujeitos participaram (idade média de 47 ± 20,74 anos). A força de preensão da mão direita foi de 32,15 ± 9,96 kg com o dinamômetro Jamar e 29,95 ± 9,18 kg com o dispositivo Camry, destacando que a equipe do Jamar possui valores maiores que o Jamar (p < 0,05). O CCC foi significativo apenas no nível populacional e na faixa etária de 40 a 59 anos. Os gráficos de Bland-Altman apresentaram limites estreitosde concordância.Conclusão. Concluímos que o dinamômetro Camry poderiasubstituir o dinamômetro Jamar na faixa etária de 40 a 59 anos;Além disso, seria apropriado para uso médico no monitoramento ou acompanhamento de pacientes devido aos valores próximos observado