Violation of the sphericity assumption and its effect on Type-I error rates in repeated measures ANOVA and multi-level linear models (MLM)

This study aims to investigate the effects of violations of the sphericity assumption on Type I error rates for different methodical approaches of repeated measures analysis using a simulation approach. In contrast to previous simulation studies on this topic, up to nine measurement occasions were considered. Therefore, two populations representing the conditions of a violation vs. a non-violation of the sphericity assumption without any between-group effect or within-subject effect were created and 5,000 random samples of each population were drawn. Finally, the mean Type I error rates for Multilevel linear models (MLM) with an unstructured covariance matrix (MLM-UN), MLM with compound-symmetry (MLM-CS) and for repeated measures analysis of variance (rANOVA) models (without correction, with Greenhouse-Geisser-correction, and Huynh-Feldt-correction) were computed. To examine the effect of both the sample size and the number of measurement occasions, sample sizes of n = 20, 40, 60, 80, and 100 were considered as well as measurement occasions of m = 3, 6 and 9. For MLM-UN, the results illustrate a massive progressive bias for small sample sizes (n =20) and m = 6 or more measurement occasions. This effect could not be found in previous simulation studies with a smaller number of measurement occasions. The mean Type I error rates for rANOVA with Greenhouse-Geisser-correction demonstrate a small conservative bias if sphericity was not violated, sample sizes were small (n = 20), and m = 6 or more measurement occasions were conducted. The results plead for a use of rANOVA with Huynh-Feldt-correction, especially when the sphericity assumption is violated, the sample size is rather small and the number of measurement occasions is large. MLM-UN may be used when the sphericity assumption is violated and when sample sizes are large.Comment: 14 pages, 6 figure

Alcohol Use, Abuse, and Dependency in Shanghai

The use of alcohol for social and ceremonial occasions was recorded in Chinese history as early as 1760 B.C. during the Yin Dynasty (Ci-Hai Encyclopedia, 1979:936). The cultural tradition of ancient China placed alcoholic beverages at the center of social occasions, which presumably was the origin of the adage: Without wine, there is no li (or etiquette). Thus, the use of alcoholic beverages has always been accompanied by the concept of propriety and the discharging of one\u27s role obligations m social functions, rather than that of personal indulgence

Finite mixtures of matrix-variate Poisson-log normal distributions for three-way count data

Three-way data structures, characterized by three entities, the units, the variables and the occasions, are frequent in biological studies. In RNA sequencing, three-way data structures are obtained when high-throughput transcriptome sequencing data are collected for n genes across p conditions at r occasions. Matrix-variate distributions offer a natural way to model three-way data and mixtures of matrix-variate distributions can be used to cluster three-way data. Clustering of gene expression data is carried out as means to discovering gene co-expression networks. In this work, a mixture of matrix-variate Poisson-log normal distributions is proposed for clustering read counts from RNA sequencing. By considering the matrix-variate structure, full information on the conditions and occasions of the RNA sequencing dataset is simultaneously considered, and the number of covariance parameters to be estimated is reduced. A Markov chain Monte Carlo expectation-maximization algorithm is used for parameter estimation and information criteria are used for model selection. The models are applied to both real and simulated data, giving favourable clustering results

Commemorative Occasions in 2002

The George Eliot Memorial Garden in Nuneaton reached its half century in May 2002. In 1930 several literary men, amongst them George Bernard Shaw, were asked if Nuneaton should erect a memorial to George Eliot. Most of them expressed astonishment that one was not already in existence. They may have been even more amazed to discover that it would be another twenty-two years before one appeared, for it was not until 1952 that the George Eliot Memorial Garden was established. The Newdegate family at Arbury Hall was one step ahead of Nuneaton as an obelisk had already been erected by Sir Francis Newdegate near to George Eliot\u27s birthplace at South Farm on the Arbury estate. The family kindly gave the obelisk to stand in the new garden in 1952 as a permanent memorial. The first plans for the garden were discussed in 1947 when a compulsory purchase order was issued to buy land in Church Street upon which \u27Dempster House\u27 (\u27Janet\u27s Repentance \u27) had stood until it was destroyed in an air raid on 17 May 1941. These negotiations clearly took time for it was not until the beginning of 1951 that an appeal for funds was made by the Mayor, Alderman W. R. Chamberlain and the Fellowship\u27s President, The Hon. Mrs. L. C. S. FitzRoy Newdegate. The total cost was expected to be about £8,000 and the Borough Council had already made what was described as a \u27handsome contribution’. Members of the small George Eliot Fellowship contributed almost £600, this having a much higher value than present day inflated figures. A competition was opened to members of the Institute of Landscape Architects and was won by Miss Mary Braendle, a joint designer with Mr. Ronald Sims. The appeal was very successful with donations coming from far afield by George Eliot admirers. The Government of Israel gave three almond trees from Jerusalem and these were planted near to the riverside. Altogether about 200 trees and shrubs were planted, many having been given by local associations and individuals

Inherent work suit buoyancy distribution:effects on lifejacket self-righting performance

Introduction: Accidental immersion in cold water is an occupational risk. Work suits and life jackets (LJ) should work effectively in combination to keep the airway clear of the water (freeboard) and enable self-righting. We hypothesized that inherent buoyancy, in the suit or LJ, would be beneficial for enabling freeboard, but its distribution may influence LJ self-righting. Methods: Six participants consented to complete nine immersions. Suits and LJ tested were: flotation suit (FLOAT; 85 N inherent buoyancy); oilskins 1 (OS-1) and 2 (OS-2), both with no inherent buoyancy; LJs (inherent buoyancy/buoyancy after inflation/total buoyancy), LJ-1 50/150/200 N, LJ-2 0/290/290 N, LJ-3 80/190/270 N. Once dressed, the subject entered an immersion pool where uninflated freeboard, self-righting performance, and inflated freeboard were measured. Data were compared using Friedman’s test to the 0.05 alpha level. Results: All suits and LJs enabled uninflated and inflated freeboard, but differences were seen between the suits and LJs. Self-righting was achieved on 43 of 54 occasions, irrespective of suit or LJ. On all occasions that self-righting was not achieved, this occurred in an LJ that included inherent buoyancy (11/54 occasions). Of these 11 failures, 8 occurred (73% of occasions) when the FLOAT suit was being worn. Discussion: LJs that included inherent buoyancy, that are certified as effective on their own, worked less effectively from the perspective of self-righting in combination with a work suit that also included inherent buoyancy. Equipment that is approved for use in the workplace should be tested in combination to ensure adequate performance in an emergency scenario

Commemorative Occasions in 2002

The George Eliot Memorial Garden in Nuneaton reached its half century in May 2002. In 1930 several literary men, amongst them George Bernard Shaw, were asked if Nuneaton should erect a memorial to George Eliot. Most of them expressed astonishment that one was not already in existence. They may have been even more amazed to discover that it would be another twenty-two years before one appeared, for it was not until 1952 that the George Eliot Memorial Garden was established. The Newdegate family at Arbury Hall was one step ahead of Nuneaton as an obelisk had already been erected by Sir Francis Newdegate near to George Eliot\u27s birthplace at South Farm on the Arbury estate. The family kindly gave the obelisk to stand in the new garden in 1952 as a permanent memorial. The first plans for the garden were discussed in 1947 when a compulsory purchase order was issued to buy land in Church Street upon which \u27Dempster House\u27 (\u27Janet\u27s Repentance \u27) had stood until it was destroyed in an air raid on 17 May 1941. These negotiations clearly took time for it was not until the beginning of 1951 that an appeal for funds was made by the Mayor, Alderman W. R. Chamberlain and the Fellowship\u27s President, The Hon. Mrs. L. C. S. FitzRoy Newdegate. The total cost was expected to be about £8,000 and the Borough Council had already made what was described as a \u27handsome contribution’. Members of the small George Eliot Fellowship contributed almost £600, this having a much higher value than present day inflated figures. A competition was opened to members of the Institute of Landscape Architects and was won by Miss Mary Braendle, a joint designer with Mr. Ronald Sims. The appeal was very successful with donations coming from far afield by George Eliot admirers. The Government of Israel gave three almond trees from Jerusalem and these were planted near to the riverside. Altogether about 200 trees and shrubs were planted, many having been given by local associations and individuals

Ecstasy/MDMA attributed problems reported by novice, moderate and heavy recreational users

The recreational use of MDMA/Ecstasy (3,4-methylenedioxymethamphetamine) is associated with many psychobiological problems, but there is a paucity of data on how these relate to the level of past use. Objectives: to assess the incidence of Ecstasy-attributed problems as reported by novice, moderate and heavy users. Methods: 763 unpaid volunteers took part in a WWW study of recreational drug use. This report is based on the 282 Ecstasy users from that sample, who comprised 109 novice users (1–9 occasions), 136 moderate users (10–99 occasions), and 36 heavy users (+100 occasions). Yes/no responses were automatically recorded to a series of questions covering psychobiological problems experienced when drug-free, which were attributed by the respondents to their Ecstasy use. Results: Depression, memory problems, anxiety, mood fluctuation, poor concentration, infections, tremors/twitches and weight loss, were all significantly associated with the extent of Ecstasy use. Thus memory problems attributed to Ecstasy were reported by 19% of novice users, 52% of heavy users and 73% of heavy users (chi-square 42.74, df=2, p<0.001); many of the other variables showed similar trends