scispace - formally typeset
Search or ask a question
Author

Graham J. G. Upton

Other affiliations: Newcastle University
Bio: Graham J. G. Upton is an academic researcher from University of Essex. The author has contributed to research in topics: Contingency table & Voting. The author has an hindex of 29, co-authored 100 publications receiving 3608 citations. Previous affiliations of Graham J. G. Upton include Newcastle University.


Papers
More filters
Journal ArticleDOI
TL;DR: In this paper, the authors argue for the use of Fisher's exact test for the analysis of 2 × 2 tables and use mid-P if a formula is required for prescribing a variable tail probability.
Abstract: This paper reviews the problems that bedevil the selection of an appropriate test for the analysis of a 2 × 2 table. In contradiction to an earlier paper, the author now argues the case for the use of Fisher's exact test. It is noted that all test statistics for the 2 × 2 table have discrete distributions and it is suggested that it is irrational to prescribe an unattainable fixed significance level. The use of mid-P is suggested, if a formula is required for prescribing a variable tail probability. The problems of two-tail tests are discussed

442 citations

Journal ArticleDOI
01 Jul 1979

189 citations

Journal ArticleDOI
01 Jan 1982
TL;DR: In this article, twenty-two alternative tests have been suggested for testing the null hypothesis Pi = P2 in a 2 x 2 comparative trial and the dependence of the tests on m and n, the sample sizes, and on p, the common binomial parameter, is investigated.
Abstract: SUMMARY This paper considers twenty-two alternative tests which have been suggested for testing the null hypothesis Pi = P2 in a 2 x 2 comparative trial. Attention is confined to the case where the null hypothesis is true. The dependence of the tests on m and n, the sample sizes, and on p, the common binomial parameter, is investigated. Amongst other results it is shown that the exact test of Fisher, and the corresponding Yates correction to Pearson's X2 test, give tests which are both extremely conservative and inappropriate. The uncorrected X2 test performs well. On both empirical and theoretical grounds, the preferred test is the scaled version (N- 1)/N X2.

167 citations

Journal ArticleDOI
TL;DR: The observation of a functionally important cluster of residues on helices 2 and 3 is novel, and some possible interpretations are given, including heterodimerization and oligomerization.
Abstract: The evolutionary trace (ET) method, a data mining approach for determining significant levels of amino acid conservation, has been applied to over 700 aligned G-protein-coupled receptor (GPCR) sequences. The method predicted the occurrence of functionally important clusters of residues on the external faces of helices 5 and 6 for each family or subfamily of receptors; similar clusters were observed on helices 2 and 3. The probability that these clusters are not random was determined using Monte Carlo techniques. The cluster on helices 5 and 6 is consistent with both 5,6-contact and 5,6-domain swapped dimer formation; the possible equivalence of these two types of dimer is discussed because this relates to activation by homo- and heterodimers. The observation of a functionally important cluster of residues on helices 2 and 3 is novel, and some possible interpretations are given, including heterodimerization and oligomerization. The application of the evolutionary trace method to 113 aligned G-protein seque...

151 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: G*Power 3 provides improved effect size calculators and graphic options, supports both distribution-based and design-based input modes, and offers all types of power analyses in which users might be interested.
Abstract: G*Power (Erdfelder, Faul, & Buchner, 1996) was designed as a general stand-alone power analysis program for statistical tests commonly used in social and behavioral research. G*Power 3 is a major extension of, and improvement over, the previous versions. It runs on widely used computer platforms (i.e., Windows XP, Windows Vista, and Mac OS X 10.4) and covers many different statistical tests of thet, F, and χ2 test families. In addition, it includes power analyses forz tests and some exact tests. G*Power 3 provides improved effect size calculators and graphic options, supports both distribution-based and design-based input modes, and offers all types of power analyses in which users might be interested. Like its predecessors, G*Power 3 is free.

40,195 citations

Book
19 Sep 2014

2,968 citations

Journal ArticleDOI
TL;DR: Four theoretical models of yes-no recognition memory are described and their associated measures of discrimination and response bias are presented and the indices from the acceptable models are used to characterize recognition memory deficits in dementia and amnesia.
Abstract: SUMMARY This article has two purposes. The first is to describe four theoretical models of yesno recognition memory and present their associated measures of discrimination and response bias. These models are then applied to a set of data from normal subjects to determine which pairs of discrimination and bias indices show independence between discrimination and bias. The following models demonstrated independence: a two-highthreshold model, a signal detection model with normal distributions using d' and C (rather than beta), and a signal detection model with logistic distributions and a bias measure analogous to C. Cis defined as the distance of criterion from the intersection of the two underlying distributions. The second purpose is to use the indices from the acceptable models to characterize recognition memory deficits in dementia and amnesia, \bung normal subjects, Alzheimer's disease patients, and parkinsonian dementia patients were tested with picture recognition tasks with repeated study-test trials. Huntington's disease patients, mixed etiology amnesics, and age-matched normals were tested by Butters, Wolfe, Martone, Granholm, and Cermak (1985) using the same paradigm with word stimuli. Demented and amnesic patients produced distinctly different patterns of abnormal memory performance. Both groups of demented patients showed poor discrimination and abnormally liberal response bias for words (Huntington's disease) and pictures (Alzheimer's disease and parkinsonian dementia), whereas the amnesic patients showed the worst discrimination but normal response bias for words. Although both signal detection theory and twohigh-threshold discrimination parameters showed identical results, the bias measure from the two-high-threshold model was more sensitive to change than the bias measure (C) from signal detection theory. Three major points are emphasized. First, any index of recognition memory performance assumes an underlying model. Second, even acceptable models can lead to different conclusions about patterns of learning and forgetting. Third, efforts to characterize and ameliorate abnormal memory should address both discrimination and bias deficits.

2,898 citations

Journal ArticleDOI
TL;DR: This paper showed that the classical models of G-protein coupling and activation of second-messenger-generating enzymes do not fully explain seven-transmembrane receptors' remarkably diverse biological actions.
Abstract: Seven-transmembrane receptors, which constitute the largest, most ubiquitous and most versatile family of membrane receptors, are also the most common target of therapeutic drugs. Recent findings indicate that the classical models of G-protein coupling and activation of second-messenger-generating enzymes do not fully explain their remarkably diverse biological actions.

2,300 citations

Journal ArticleDOI
TL;DR: In this article, the spatial heterogeneity of populations and communities plays a central role in many ecological theories, such as succession, adaptation, maintenance of species diversity, community stability, competition, predator-prey interactions, parasitism, epidemics and other natural catastrophes, ergoclines, and so on.
Abstract: The spatial heterogeneity of populations and communities plays a central role in many ecological theories, for instance the theories of succession, adaptation, maintenance of species diversity, community stability, competition, predator-prey interactions, parasitism, epidemics and other natural catastrophes, ergoclines, and so on. This paper will review how the spatial structure of biological populations and communities can be studied. We first demonstrate that many of the basic statistical methods used in ecological studies are impaired by autocorrelated data. Most if not all environmental data fall in this category. We will look briefly at ways of performing valid statistical tests in the presence of spatial autocorrelation. Methods now available for analysing the spatial structure of biological populations are described, and illustrated by vegetation data. These include various methods to test for the presence of spatial autocorrelation in the data: univariate methods (all-directional and two-dimensional spatial correlograms, and two-dimensional spectral analysis), and the multivariate Mantel test and Mantel correlogram; other descriptive methods of spatial structure: the univariate variogram, and the multivariate methods of clustering with spatial contiguity constraint; the partial Mantel test, presented here as a way of studying causal models that include space as an explanatory variable; and finally, various methods for mapping ecological variables and producing either univariate maps (interpolation, trend surface analysis, kriging) or maps of truly multivariate data (produced by constrained clustering). A table shows the methods classified in terms of the ecological questions they allow to resolve. Reference is made to available computer programs.

2,166 citations