RESUMO
A crossbred (Sindhi x local indigenous) calf that was 12 days old was admitted to the Teaching Veterinary Hospital, Chittagong Government Veterinary College, Bangladesh, with two accessory hind limbs attached to the pelvic region in between the hind legs. This was clinically identified as a congenital anomaly popularly called pygomelia. The pygomelia was successfully corrected by surgical excisions.
Assuntos
Doenças dos Bovinos/congênito , Membro Posterior/anormalidades , Deformidades Congênitas dos Membros/veterinária , Animais , Bovinos , Doenças dos Bovinos/genética , Doenças dos Bovinos/cirurgia , Membro Posterior/cirurgia , Hibridização Genética , Deformidades Congênitas dos Membros/genética , Deformidades Congênitas dos Membros/cirurgiaRESUMO
Liang and Zeger (1986, Biometrika 73, 13-22) introduced a generalized estimating equation (GEE) approach based on a working correlation matrix to obtain efficient estimators of regression parameters in the class of generalized linear models for repeated measures data. As demonstrated by Crowder (1995, Biometrika 82, 407-410), because of uncertainty of the definition of the working correlation matrix, the Liang-Zeger approach may, in some cases, lead to a complete breakdown of the estimation of the regression parameters. After taking this comment of Crowder into account, recently Sutradhar and Das (1999, Biometrika 86, 459-465) examined the loss of efficiency of the regression estimators due to misspecification of the correlation structures. But their study was confined to the regression estimation with cluster-level covariates, as in the original paper of Liang and Zeger. In this paper, we study this efficiency loss problem for the generalized regression models with within-cluster covariates by utilizing the approach of Sutradhar and Das (1999).
Assuntos
Biometria/métodos , Estudos Longitudinais , Análise por Conglomerados , Interpretação Estatística de Dados , Humanos , Análise de Regressão , Reprodutibilidade dos Testes , Fatores de TempoRESUMO
A review is given of the literature on time-series valued experimental designs. Most of this literature is divided into two categories depending upon the factor status of the time variable. In one category, time is an experimental factor, and in the other it is a non-specific factor and enters the design in the context of replications. Analyses in both the time and frequency domain are reviewed. Signal detection models, Bayesian methods and optimal designs are surveyed. A discussion is also presented of application areas which include field trials and medical experiments. A main theme of the literature is that application of standard F-tests to highly correlated data can be misleading. A bibliography of relevant publications from 1949 onward is presented.
