Hon Keung Tony Ng

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One of the most basic topics in many introductory statistical methods texts is inference for a population mean, μ. The primary tool for confidence intervals and tests is the Student t sampling distribution. Although the derivation requires independent identically distributed normal random variables with constant variance, σ, most authors reassure the(More)
In this article, we investigate procedures for comparing two independent Poisson variates that are observed over unequal sampling frames (i.e. time intervals, populations, areas or any combination thereof). We consider two statistics (with and without the logarithmic transformation) for testing the equality of two Poisson rates. Two methods for implementing(More)
The Cochran-Armitage trend test (CATT) is well suited for testing association between a marker and a disease in case-control studies. When the underlying genetic model for the disease is known, the CATT optimal for the genetic model is used. For complex diseases, however, the genetic models of the true disease loci are unknown. In this situation, robust(More)
In this paper we compare the properties of four different general approaches for testing the ratio of two Poisson rates. Asymptotically normal tests, tests based on approximate p -values, exact conditional tests, and a likelihood ratio test are considered. The properties and power performance of these tests are studied by a Monte Carlo simulation(More)
Performances of some common confidence interval construction procedures for direct standardized incidence or mortality rate were compared. The asymptotic method, the method based on matching moments, the method based on gamma distribution and the method based on beta distribution were investigated through Monte Carlo simulations based on data from an(More)
The aim of this study was to validate the single nucleotide polymorphisms (SNPs) of four candidate genes (TCF7L2, HHEX, KCNJ11, and ADIPOQ) related to type 2 diabetes (T2D) in an endogamous population of north India; the Aggarwal population, having 18-clans. This endogamous population model was heavily supported by recent land mark work and we also verified(More)