In this article, we utilize stochastic search variable selection methodology to develop a Bayesia... more In this article, we utilize stochastic search variable selection methodology to develop a Bayesian method for identifying multiple quantitative trait loci (QTL) for complex traits in experimental designs. The proposed procedure entails embedding multiple regression in a hierarchical normal mixture model, where latent indicators for all markers are used to identify the multiple markers. The markers with significant effects can be identified as those with higher posterior probability included in the model. A simple and easy-to-use Gibbs sampler is employed to generate samples from the joint posterior distribution of all unknowns including the latent indicators, genetic effects for all markers, and other model parameters. The proposed method was evaluated using simulated data and illustrated using a real data set. The results demonstrate that the proposed method works well under typical situations of most QTL studies in terms of number of markers and marker density.
Defining 'geographic signature' as a firm's national presence, we apply it to the pha... more Defining 'geographic signature' as a firm's national presence, we apply it to the pharmaceutical and biotechnology industries, deemed as 'alter' to each other. Higher firm performance is associated with greater sub-unit scattering. Proximity to firms in the 'alter' industry has surprising adverse effects, but none with firms in the 'ego' industry.
International Journal of Technology Management, Apr 30, 1995
Abstract: Anchored on theory of technological innovation and structural theory, and using a compr... more Abstract: Anchored on theory of technological innovation and structural theory, and using a comprehensive dataset of US-centred global alliances for 1985-1990, the paper shows the overwhelming influence of technological intensity in the formation of interfirm alliances. ...
Motivation: Methods are needed to test pre-defined genomic regions such as promoters for differen... more Motivation: Methods are needed to test pre-defined genomic regions such as promoters for differential methylation in genome-wide association studies, where the number of samples is limited and the data have large amounts of measurement error. Results: We developed a new statistical test, the generalized integrated functional test (GIFT), which tests for regional differences in methylation based on differences in the functional relationship between methylation percent and location of the CpG sites within a region. In this method, subject-specific functional profiles are first estimated, and the average profile within groups is compared between groups using an ANOVA-like test. Simulations and analyses of data obtained from patients with chronic lymphocytic leukemia indicate that GIFT has good statistical properties and is able to identify promising genomic regions. Further, GIFT is likely to work with multiple different types of experiments since different smoothing functions can be u...
Rare genetic variants have been shown to be important to the susceptibility of common human disea... more Rare genetic variants have been shown to be important to the susceptibility of common human diseases. Methods for detecting association of rare genetic variants are drawing much attention. In this report, we applied a gene-based approach to the 200 simulated data sets of unrelated individuals. The test can detect the association of some genes with multiple rare variants.
Genome-wide association studies are very powerful in determining the genetic variants affecting c... more Genome-wide association studies are very powerful in determining the genetic variants affecting complex diseases. Most of the available methods are very useful in detecting association between common variants and complex diseases. Recently, methods to detect rare variants in association with complex diseases have been developed with the increasingly available sequencing data from next-generation sequencing. In this paper, we evaluate and compare several of these recent methods for performing statistical association using whole genome sequencing data in pedigrees. Specifically, functional principal component analysis (FPCA), extended combined multivariate and collapsing (CMC) method for families, a generalized T(2) method, and chi-square minimum approach were compared by analyzing all the genetic variants, common and rare, of both the real data set and the simulated data set provided as part of Genetic Analysis Workshop 18.
Regression to the mean arises often in statistical applications where the units chosen for study ... more Regression to the mean arises often in statistical applications where the units chosen for study relate to some observed characteristic in the extreme of its distribution. Gardner and Heady attribute the effect of regression to the mean to measurement errors. They assume the model Yi = U + ei, where U is a fixed within-subject component and ei is the random measurement error. They suggest several replicate measurements to reduce the regression effect under the assumption that the measurement errors ei are independent within subjects. While measurement errors play an important role in regression to the mean, one should not overlook within-subject variation. In this paper, we consider a model to estimate the regression effect in the presence of correlated within-subject effects as well as independent measurement errors.
Confidence limits for population prevalence based on the first occurrence of an item in a medical... more Confidence limits for population prevalence based on the first occurrence of an item in a medical database, or for incidence based on time to first occurrence, should be based on the geometric or exponential distributions, respectively. These intervals are presented and compared with the corresponding intervals based on the binomial and Poisson distributions. The lower confidence limits are shown to be the same, but the upper limits are smaller, hence leading to shorter intervals. Applications of these intervals are also presented.
... This article is, firstly, a brief historical account of Cypriot immigra-tion to the United Ki... more ... This article is, firstly, a brief historical account of Cypriot immigra-tion to the United Kingdom. ... This includes first generation Cypriot immigrants and second generation Cypriot children born in this country. ... Demographic Report, Republic of Cyprus (1963). ...
In this article, we utilize stochastic search variable selection methodology to develop a Bayesia... more In this article, we utilize stochastic search variable selection methodology to develop a Bayesian method for identifying multiple quantitative trait loci (QTL) for complex traits in experimental designs. The proposed procedure entails embedding multiple regression in a hierarchical normal mixture model, where latent indicators for all markers are used to identify the multiple markers. The markers with significant effects can be identified as those with higher posterior probability included in the model. A simple and easy-to-use Gibbs sampler is employed to generate samples from the joint posterior distribution of all unknowns including the latent indicators, genetic effects for all markers, and other model parameters. The proposed method was evaluated using simulated data and illustrated using a real data set. The results demonstrate that the proposed method works well under typical situations of most QTL studies in terms of number of markers and marker density.
Defining 'geographic signature' as a firm's national presence, we apply it to the pha... more Defining 'geographic signature' as a firm's national presence, we apply it to the pharmaceutical and biotechnology industries, deemed as 'alter' to each other. Higher firm performance is associated with greater sub-unit scattering. Proximity to firms in the 'alter' industry has surprising adverse effects, but none with firms in the 'ego' industry.
International Journal of Technology Management, Apr 30, 1995
Abstract: Anchored on theory of technological innovation and structural theory, and using a compr... more Abstract: Anchored on theory of technological innovation and structural theory, and using a comprehensive dataset of US-centred global alliances for 1985-1990, the paper shows the overwhelming influence of technological intensity in the formation of interfirm alliances. ...
Motivation: Methods are needed to test pre-defined genomic regions such as promoters for differen... more Motivation: Methods are needed to test pre-defined genomic regions such as promoters for differential methylation in genome-wide association studies, where the number of samples is limited and the data have large amounts of measurement error. Results: We developed a new statistical test, the generalized integrated functional test (GIFT), which tests for regional differences in methylation based on differences in the functional relationship between methylation percent and location of the CpG sites within a region. In this method, subject-specific functional profiles are first estimated, and the average profile within groups is compared between groups using an ANOVA-like test. Simulations and analyses of data obtained from patients with chronic lymphocytic leukemia indicate that GIFT has good statistical properties and is able to identify promising genomic regions. Further, GIFT is likely to work with multiple different types of experiments since different smoothing functions can be u...
Rare genetic variants have been shown to be important to the susceptibility of common human disea... more Rare genetic variants have been shown to be important to the susceptibility of common human diseases. Methods for detecting association of rare genetic variants are drawing much attention. In this report, we applied a gene-based approach to the 200 simulated data sets of unrelated individuals. The test can detect the association of some genes with multiple rare variants.
Genome-wide association studies are very powerful in determining the genetic variants affecting c... more Genome-wide association studies are very powerful in determining the genetic variants affecting complex diseases. Most of the available methods are very useful in detecting association between common variants and complex diseases. Recently, methods to detect rare variants in association with complex diseases have been developed with the increasingly available sequencing data from next-generation sequencing. In this paper, we evaluate and compare several of these recent methods for performing statistical association using whole genome sequencing data in pedigrees. Specifically, functional principal component analysis (FPCA), extended combined multivariate and collapsing (CMC) method for families, a generalized T(2) method, and chi-square minimum approach were compared by analyzing all the genetic variants, common and rare, of both the real data set and the simulated data set provided as part of Genetic Analysis Workshop 18.
Regression to the mean arises often in statistical applications where the units chosen for study ... more Regression to the mean arises often in statistical applications where the units chosen for study relate to some observed characteristic in the extreme of its distribution. Gardner and Heady attribute the effect of regression to the mean to measurement errors. They assume the model Yi = U + ei, where U is a fixed within-subject component and ei is the random measurement error. They suggest several replicate measurements to reduce the regression effect under the assumption that the measurement errors ei are independent within subjects. While measurement errors play an important role in regression to the mean, one should not overlook within-subject variation. In this paper, we consider a model to estimate the regression effect in the presence of correlated within-subject effects as well as independent measurement errors.
Confidence limits for population prevalence based on the first occurrence of an item in a medical... more Confidence limits for population prevalence based on the first occurrence of an item in a medical database, or for incidence based on time to first occurrence, should be based on the geometric or exponential distributions, respectively. These intervals are presented and compared with the corresponding intervals based on the binomial and Poisson distributions. The lower confidence limits are shown to be the same, but the upper limits are smaller, hence leading to shorter intervals. Applications of these intervals are also presented.
... This article is, firstly, a brief historical account of Cypriot immigra-tion to the United Ki... more ... This article is, firstly, a brief historical account of Cypriot immigra-tion to the United Kingdom. ... This includes first generation Cypriot immigrants and second generation Cypriot children born in this country. ... Demographic Report, Republic of Cyprus (1963). ...
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Papers by VARGHESE George