Finding the magic number

Paul Wilson and Colin Cooper investigate methods used to extract the number of factors in a factor analysis

Unite and conquer: univariate and multivariate approaches for finding differentially expressed gene sets

Motivation: Recently, many univariate and several multivariate approaches have been suggested for testing differential expression of gene sets between different phenotypes. However, despite a wealth of literature studying their performance on simulated and real biological data, still there is a need to quantify their relative performance when they are testing different null hypotheses.

Results: In this article, we compare the performance of univariate and multivariate tests on both simulated and biological data. In the simulation study we demonstrate that high correlations equally affect the power of both, univariate as well as multivariate tests. In addition, for most of them the power is similarly affected by the dimensionality of the gene set and by the percentage of genes in the set, for which expression is changing between two phenotypes. The application of different test statistics to biological data reveals that three statistics (sum of squared t-tests, Hotelling's T2, N-statistic), testing different null hypotheses, find some common but also some complementing differentially expressed gene sets under specific settings. This demonstrates that due to complementing null hypotheses each test projects on different aspects of the data and for the analysis of biological data it is beneficial to use all three tests simultaneously instead of focusing exclusively on just one.

The finding of reduced estimated glomerular filtration rate is associated with increased mortality in a large UK population

BACKGROUND: CKD as defined by KDIGO/KDOQI has been shown to affect ~ 8.5% of the UK population. The prevalence of CKD in the UK is similar to that in the USA, yet incident dialysis rates are dramatically different. This retrospective cohort study investigates the association between reduced kidney function and mortality in a large UK population. METHODS: All serum creatinine results covering Northern Ireland's 1.7 million population were collected between 1 January 2001 and 31 December 2002. Estimated glomerular filtration rates (eGFR) were calculated for all serum creatinine measurements using four-variable MDRD equation (IDMS aligned). Patients were followed up for both all-cause and cardiovascular mortality data until the end of December 2006. Patients on renal replacement therapy were excluded. Subgroup analysis in the 75 345 subjects enrolled within a parallel primary care study permitted additional survival analysis with adjustment for traditional cardiovascular risk factors. RESULTS: A total of 1 967 827 serum creatinine results from 533 798 patients were collected. During the period of follow-up, 59 980 deaths occurred. In multivariate survival analysis, using eGFR as a time-varying covariate, a graded association between CKD (defined by eGFR) and all-cause mortality was identified. Compared with participants with an eGFR of > 60 mL/min/1.73 m(2), the adjusted hazard ratios (and 95% confidence intervals) for participants with an eGFR of 45-59 mL/min/1.73 m(2) was 1.02 (0.99-1.04), an eGFR of 30-44 mL/min/1.73 m(2) was 1.44 (1.40-1.47), an eGFR of 15-29 mL/min/1.73 m(2) was 2.12 (2.05-2.20) and an eGFR of

History of Child Welfare and Protection Social Work in Northern Ireland: Finding Continuity amongst Discontinuity in Case Files from 1950-1968

This article reports on research carried out on 200 child welfare files from the largest welfare authority in Northern Ireland from 1950-1968. The literature review provides a commentary on some of the major debates surrounding child welfare and protection social work from the perspective of its historical development. The report of the research which follows offers an insight into one core, and less well-known period of child welfare history in Northern Ireland between the two Children and Young Persons Acts (1950 & 1968). Using a method of discourse analysis influenced by Michel Foucault, a detailed description of the nature of practice is offered. This paper is offered as a work in progress, with further work being planned for dissemination of more detailed analysis of the method and outcomes. The research seeks to ask a few core questions based on problems identified in the present with our current understandings of child welfare and protection histories. While recognising the limitations of this study and the need for broader analysis of the wider context surrounding child welfare practice at the moment, it is argued that some salient conclusions can be drawn about continuity and discontinuity in practice which are of interest to practitioners and students of child welfare social work.

Recovery from brain injury: Finding the missing bits of the puzzle

Background: One basic problem found during rehabilitation is that people with brain injuries lack awareness of their difficulties. Research into this phenomenon has often disregarded the voices of those affected by the trauma and do not give an insider's perspective on the process through which a person with a brain injury develops awareness of their difficulties.