Modifications and Alternatives to the Tests of Levene and Brown & Forsythe for Equality of Variances and Means

The usual tests to compare variances and means (e. g. Bartlett`s test and F-test) assume that the sample comes from a normal distribution. In addition, the test for equality of means requires the assumption of homogeneity of variances. In some situation those assumptions are not satisfied, hence we may face problems like excessive size and low power. In this paper, we describe two tests, namely the Levene`s test for equality of variances, which is robust under nonnormality; and the Brown and Forsythe`s test for equality of means. We also present some modifications of the Levene`s test and Brown and Forsythe`s test, proposed by different authors. We analyzed and applied one modified form of Brown and Forsythe`s test to a real data set. This test is a robust alternative under nonnormality, heteroscedasticity and also when the data set has influential observations. The equality of variance can be well tested by Levene`s test with centering at the sample median.

Some restriction tests in a new class of regression models for proportions

The main purpose of this work is to study the behaviour of Skovgaard`s [Skovgaard, I.M., 2001. Likelihood asymptotics. Scandinavian journal of Statistics 28, 3-32] adjusted likelihood ratio statistic in testing simple hypothesis in a new class of regression models proposed here. The proposed class of regression models considers Dirichlet distributed observations, and the parameters that index the Dirichlet distributions are related to covariates and unknown regression coefficients. This class is useful for modelling data consisting of multivariate positive observations summing to one and generalizes the beta regression model described in Vasconcellos and Cribari-Neto [Vasconcellos, K.L.P., Cribari-Neto, F., 2005. Improved maximum likelihood estimation in a new class of beta regression models. Brazilian journal of Probability and Statistics 19,13-31]. We show that, for our model, Skovgaard`s adjusted likelihood ratio statistics have a simple compact form that can be easily implemented in standard statistical software. The adjusted statistic is approximately chi-squared distributed with a high degree of accuracy. Some numerical simulations show that the modified test is more reliable in finite samples than the usual likelihood ratio procedure. An empirical application is also presented and discussed. (C) 2009 Elsevier B.V. All rights reserved.

Local power of some tests in exponential family nonlinear models

In this paper we obtain asymptotic expansions up to order n(-1/2) for the nonnull distribution functions of the likelihood ratio, Wald, score and gradient test statistics in exponential family nonlinear models (Cordeiro and Paula, 1989), under a sequence of Pitman alternatives. The asymptotic distributions of all four statistics are obtained for testing a subset of regression parameters and for testing the dispersion parameter, thus generalising the results given in Cordeiro et al. (1994) and Ferrari et al. (1997). We also present Monte Carlo simulations in order to compare the finite-sample performance of these tests. (C) 2010 Elsevier B.V. All rights reserved.

In vitro tests to establish LC(50) and discriminating concentrations for fipronil against Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) and their standardization

Laboratory test was carried out on larvae and adults of the cattle tick, Rhipicephalus (Boophilus) microplus, to determine fipronil toxicity. Adult immersion test (AIT, N = 26), larval immersion test (LIT, N = 71) and larval packet test (LPT, N = 41) were standardized using susceptible strain (Mozo). Dose-response curves were compared with a fipronil resistant strain. Four variables were analyzed from AIT results: mortality, weight of eggs on day 7 and on day 14, index of fertility, and index of fecundity. For larval test, dose mortality curves were analyzed. In spite of the high LC(50) variability, all variables determined for AIT were appropriate to discriminate both strains. AIT and LIT had more sensitivity than LPT, with larger resistance factors. It was used two times LC(99.9) as discriminating doses (DCs) following FAO suggestion. For mortality by AIT, LIT and LPT the DCs were estimated: 4.98 ppm, 7.64 ppm and 2365.8 ppm, respectively, for Mozo strain. DCs mortality values estimated for resistant strain by AIT, LIT and LPT were: 6.96 x 10(5) ppm, 343.26 ppm and 5.7 x 10(3) ppm, respectively and their respective resistant factors were: 202.4, 5.36 and 1.52. Protocols for AIT, LIT and LPT have been presented in this paper. (C) 2009 Elsevier B.V. All rights reserved.

Machine vision for the automatic classification of images acquired from Non-destructive tests

This project is based on Artificial Intelligence (A.I) and Digital Image processing (I.P) for automatic condition monitoring of sleepers in the railway track. Rail inspection is a very important task in railway maintenance for traffic safety issues and in preventing dangerous situations. Monitoring railway track infrastructure is an important aspect in which the periodical inspection of rail rolling plane is required.Up to the present days the inspection of the railroad is operated manually by trained personnel. A human operator walks along the railway track searching for sleeper anomalies. This monitoring way is not more acceptable for its slowness and subjectivity. Hence, it is desired to automate such intuitive human skills for the development of more robust and reliable testing methods. Images of wooden sleepers have been used as data for my project. The aim of this project is to present a vision based technique for inspecting railway sleepers (wooden planks under the railway track) by automatic interpretation of Non Destructive Test (NDT) data using A.I. techniques in determining the results of inspection.

Universal Experimental Measurement System «Sun-Walker» : Automotive measurement system for the evaluation of the solar irradiation distribution for the tests of the solar concentrated systems.

This Thesis project is a part of the research conducted in Solar industry. ABSOLICON Solar Concentrator AB has invented and started production of the prospective solar concentrated system Absolicon X10. The aims of this Thesis project are designing, assembling, calibrating and putting in operation the automatic measurement system intended to evaluate distribution of density of solar radiation in the focal line of the concentrated parabolic reflectors and to measure radiation from the artificial source of light being a calibration-testing tool.On the basis of the requirements of the company’s administration and needs of designing the concentrated reflectors the operation conditions for the Sun-Walker were formulated. As the first step, the complex design of the whole system was made and division on the parts was specified. After the preliminary conducted simulation of the functions and operation conditions of the all parts were formulated.As the next steps, the detailed design of all the parts was made. Most components were ordered from respective companies. Some of the mechanical components were made in the workshop of the company. All parts of the Sun-Walker were assembled and tested. The software part, which controls the Sun-Walker work and conducts measurements of solar irradiation, was created on the LabVIEW basis. To tune and test the software part, the special simulator was designed and assembled.When all parts were assembled in the complete system, the Sun-Walker was tested, calibrated and tuned.

1 Étude comparative de prépositions suédoises et françaises dans Pippi Långstrump et sa traduction en français

Le but général de ce mémoire est d’étudier les prépositions en suédois et en français. A partir de certaines catégories de prépositions nous allons faire une analyse de la traduction des prépositions suédoises en français et des difficultés qui peuvent surgir pendant la traduction. Pour voir cela nous allons faire une étude comparative à base des livres de Pippi Långstrump d’Astrid Lindgren et leur traduction en français, Fifi Brindacier.

Beneftis of modularity and module level tests

Many companies implement a modular architecture to support the need to create more variants with less effort. Although the modular architecture has many benefits, the tests to detect any defects become a major challenge. However, a modular architecture with defined functional elements seems beneficial to test at module level, so called MPV (Module Property Verification). This paper presents studies from 29 companies with the purpose of showing trends in the occurrence of defects and how these can support the MPV.

Self-reported symptoms and motor tests via telemetry in a 36-month levodopa-carbidopa intestinal gel infusion trial

Objective To investigate if a home environment test battery can be used to measure effects of Parkinson’s disease (PD) treatment intervention and disease progression. Background Seventy-seven patients diagnosed with advanced PD were recruited in an open longitudinal 36-month study at 10 clinics in Sweden and Norway; 40 of them were treated with levodopa-carbidopa intestinal gel (LCIG) and 37 patients were candidates for switching from oral PD treatment to LCIG. They utilized a mobile device test battery, consisting of self-assessments of symptoms and objective measures of motor function through a set of fine motor tests (tapping and spiral drawings), in their homes. Both the LCIG-naïve and LCIG-non-naïve patients used the test battery four times per day during week-long test periods. Methods Assessments The LCIG-naïve patients used the test battery at baseline (before LCIG), month 0 (first visit; at least 3 months after intraduodenal LCIG), and thereafter quarterly for the first year and biannually for the second and third years. The LCIG-non-naïve patients used the test battery from the first visit, i.e. month 0. Out of the 77 patients, only 65 utilized the test battery; 35 were LCIG-non-naïve and 30 LCIG-naïve. In 20 of the LCIG-naïve patients, assessments with the test battery were available during oral treatment and at least one test period after having started infusion treatment. Three LCIG-naïve patients did not use the test battery at baseline but had at least one test period of assessments thereafter. Hence, n=23 in the LCIG-naïve group. In total, symptom assessments in the full sample (including both patient groups) were collected during 379 test periods and 10079 test occasions. For 369 of these test periods, clinical assessments including UPDRS and PDQ-39 were performed in afternoons at the start of the test periods. The repeated measurements of the test battery were processed and summarized into scores representing patients’ symptom severities over a test period, using statistical methods. Six conceptual dimensions were defined; four subjectively-reported: ‘walking’, ‘satisfied’, ‘dyskinesia’, and ‘off’ and two objectively-measured: ‘tapping’ and ‘spiral’. In addition, an ‘overall test score’ (OTS) was defined to represent the global health condition of the patient during a test period. Statistical methods Change in the test battery scores over time, that is at baseline and follow-up test periods, was assessed with linear mixed-effects models with patient ID as a random effect and test period as a fixed effect of interest. The within-patient variability of OTS was assessed using intra-class correlation coefficient (ICC), for the two patient groups. Correlations between clinical rating scores and test battery scores were assessed using Spearman’s rank correlations (rho). Results In LCIG-naïve patients, mean OTS compared to baseline was significantly improved from the first test period on LCIG treatment until month 24. However, there were no significant changes in mean OTS scores of LCIG-non-naïve patients, except for worse mean OTS at month 36 (p<0.01, n=16). The mean scores of all subjectively-reported dimensions improved significantly throughout the course of the study, except ‘walking’ at month 36 (p=0.41, n=4). However, there were no significant differences in mean scores of objectively-measured dimensions between baseline and other test periods, except improved ‘tapping’ at month 6 and month 36, and ‘spiral’ at month 3 (p<0.05). The LCIG-naïve patients had a higher within-subject variability in their OTS scores (ICC=0.67) compared to LCIG-non-naïve patients (ICC=0.71). The OTS correlated adequately with total UPDRS (rho=0.59) and total PDQ-39 (rho=0.59). Conclusions In this 3-year follow-up study of advanced PD patients treated with LCIG we found that it is possible to monitor PD progression over time using a home environment test battery. The significant improvements in the mean OTS scores indicate that the test battery is able to measure functional improvement with LCIG sustained over at least 24 months.

Un voyage interculturel Maghreb – France – Suède. Les romans de Faïza Guène en version originale et en traduction suédoise

Cet article porte sur les deux premiers romans de Faïza Guène : Kiffe kiffe demain (2004) et Du rêve pour les oufs (2006), ainsi que les traductions en langue suédoise : Kiffe kiffe imorgon (2006) et Drömmar för dårar (2008). Nous présentons d’abord quelques mots et expressions dans les textes originaux qui sont porteurs de la culture maghrébine, pour voir comment ces termes sont traduits en suédois. Ensuite, nous discutons quelques mots qui sont porteurs de la culture française. L’étude porte également sur l’oralité et le registre argotique, qui sont des traits caractéristiques de la prose de Faïza Guène. Or, si l’oralité est, dans l’ensemble, bien transférée en langue suédoise, il s’est avéré impossible de la rendre par les mêmes moyens dans la langue cible. Par conséquent, le procédé de compensation est fréquemment utilisé dans les textes traduits. Une conclusion de notre étude est que le côté argotique et « beur » des ouvrages est un peu moins développé dans les traductions que dans les textes originaux. Pour cette raison, on peut parler d’un procédé de normalisation : le texte cible a parfois tendance à devenir moins singulier – ou, si l’on veut, plus « normal », plus « neutre » que le texte source.

Faïza Guène chez les Vikings : quelques réflexions à propos de la traduction suédoise d’un discours argotique et "beur"

L’article porte sur les deux premiers romans de Faïza Guène : Kiffe kiffe demain (2004) et Du rêve pour les oufs (2006), ainsi que sur les traductions en langue suédoise Kiffe kiffe imorgon (2006) et Drömmar för dårar (2008). Nous nous intéressons aux mots et aux expressions qui sont porteurs de la culture maghrébine, pour voir comment ces termes sont traduits en suédois. Nous étudions aussi l’oralité et le registre argotique, qui sont des traits caractéristiques de la prose de Guène. Nous constatons que certains termes d’origine arabe du texte source sont traduits par des mots ayant une autre étymologie, ce qui rend la présence maghrébine un peu moins visible dans le texte cible. Nous constatons aussi que l’oralité du texte source est transférée dans le texte cible, mais par d’autres moyens – un procédé de compensation est souvent utilisé. Le registre argotique paraît un peu plus saillant dans les romans français que dans les versions traduites. L’exemple le plus frappant est le discours des personnages dans Du rêve pour les oufs, qui doit être traduit en « français standard » par le moyen de notes de bas de page, pour assurer la compréhension du lecteur implicite du texte original – phénomène qui n’a pas d’équivalent dans la traduction suédoise. Ce procédé de normalisation rend le texte cible plus neutre et, peut-être, un peu moins singulier que l’original.

Le long trajet vers le Nord : de la traduction de la littérature de jeunesse française en suédois

Depuis très récemment, un changement est en train de se produire dans le domaine de la traduction de la littérature jeunesse: auparavant et pendant de nombreuses années, les ouvrages traduits venaient le plus souvent de la Suède pour être traduits en français (Gossas & Lindgren, 2011). Dans l’autre sens, on trouvait des imagiers plus ou moins sans texte, des bandes-dessinées (surtout franco-belges), des retraductions et quelques classiques comme les très populaires ouvrages de Jules Verne ou Le Petit Prince. Or, la littérature jeunesse française est certes abondante – et ce même si l’on s’en tient aux livres publiés en France, mais aussi souvent de grande qualité littéraire et iconique, ce qui devrait a priori encourager sa diffusion. Cette littérature a de surcroît la chance de pouvoir surfer sur la vague actuelle des traductions du français au suédois de livres ne faisant pas partie de cette catégorie. Mais il est bien connu que le système littéraire suédois de la littérature jeunesse comporte peu de livres traduits, en dehors des traductions massives d’ouvrages en anglais. Les questions auxquelles nous répondrons lors de notre présentation sont : Quels sont les livres actuellement traduits du français vers le suédois ? Qui les traduit (quels éditeurs et quels traducteurs) ? Nous allons ainsi montrer quelle a été l’évolution depuis 1970 jusqu’à nos jours. Nous ferons aussi le lien avec nos études précédentes concernant le sens inverse, c’est-à-dire la traduction en français de la littérature suédoise contemporaine pour la jeunesse et de nos résultats en la matière sur les livres traduits, les éditeurs et les traducteurs. Nous utiliserons comme base théorique la théorie du polysystème (Even-Zohar), notamment concernant le rôle de la littérature traduite dans un système littéraire, et les études descriptives de la traduction (voir Toury, Shavit, etc.).