¹Universidade Estadual de Campinas, Instituto de Matemática Estatí stica e Computação Científica, Departamento de Estatística, Campinas, Brasil. Professor. Email: rtovar34@hotmail.com
²Universidade de São Paulo, Faculdade de Saúde, Departamento de Medicina Social FMRP, Riberão Preto, Brasil. Professor. Email: achacar@fmrp.usp.br

In many practical situations, clinical diagnostic procedures include two or more biological traits whose outcomes are expressed on a continuous scale and are then dichotomized using a cut point. As measurements are performed on the same individual there is a likely correlation between the continuous underlying traits that can go unnoticed when the parameter estimation is done with the resulting binary variables. In this paper, we compare the performance of two different indexes developed to evaluate the dependence between diagnostic clinical tests that assume binary structure in the results with the performance of the binary covariance and two copula dependence parameters.

Key words: Copula, Farlie Gumbel Morgenstern distribution, Gumbel distribution.

Muchos procedimientos de diagnóstico clínico médico exigen la evaluación de dos o mas rasgos biológicos que se ven alterados ante la presencia de fenómenos de enfermedad o infección, los cuales se expresan en una escala contínua de medición con posterior dicotomización usando de un valor límite o punto de corte. Dado que las mediciones son realizadas en el mismo indivíduo, los resultados probablemente presenten dependencia de algún tipo, lo cual puede ser ignorado en la etapa de análisis de datos dada la presentación binaria de los datos. En este estudio comparamos el comportamiento de dos parámetros de dependencia presentes en funciones de cópula con el de la covarianza binaria y dos índices creados para medir dependencia entre pruebas diagnósticas de respuesta dicótoma.

Palabras clave: cópula, distribución Farlie, Gumbel.

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