Estimation in generalized linear models with random effects

Schall, Robert

doi:10.1093/biomet/78.4.719

Cited by 1,025 publications

(625 citation statements)

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“…Two transformations of the sample variance are analysed by a linear mixed model (LMM; Henderson, 1953). Furthermore, a generalized linear mixed model (GLMM;McCullagh and Nelder, 1989;Schall, 1991) is applied to the untransformed sample variance within litter. The significance of the sex effect on birth weight variability is tested by an F-test with adjusted denominator degrees of freedom (Kenward and Roger, 1997).…”

Section: Introductionmentioning

confidence: 99%

Comparison of statistical models to analyse the genetic effect on within-litter variance in pigs

Wittenburg

Guiard

Teuscher

et al. 2008

Animal

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Genetics affects not only the weight of piglets at birth but also the variability of birth weight within litter. Previous studies on this topic assigned the sample standard deviation of piglet birth weights within litter as an observation to the sow. However, the contribution of the difference in mean birth weight per sex on the within-litter variance has been neglected so far. This work deals with the genetic effect on within-litter variance when different statistical models with different distributional assumptions are used and considers the sex effect and appropriate weights per trait. Traits were formed from the pooled sample variance of male and female birth weights within litter. A linear model approach was fitted to the logarithmized within-litter variance and the sample standard deviation. A generalized linear model with gamma-distributed residuals and log-link function was applied to the untransformed sample variance. Models were compared by analysing data from 9439 litters from Landrace and Large White of a commercial breeding programme. The estimates of heritability for different traits ranged from 7% to 11%. Although the generalized linear mixed model is preferred from a mathematical view, the rank correlations between breeding values of the linear mixed models and the generalized linear mixed model were relatively high, i.e. 94% to 98%. By residual diagnostics, a linear mixed model using the weighted and pooled within-litter standard deviation was identified as most suitable.

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Section: Introductionmentioning

confidence: 99%

Comparison of statistical models to analyse the genetic effect on within-litter variance in pigs

Wittenburg

Guiard

Teuscher

et al. 2008

Animal

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“…Statistical analysis was done by the Center of Quantitative Analysis of the Medical School of Ribeirão Preto USP (CEMEQ) using a linear model with mixed effects (19) . The model was adjusted using the Proc Mixed feature of the SAS software package version 9 (15) .…”

Section: Methodsmentioning

confidence: 99%

Effect of Gum Chewing on Air Swallowing, Saliva Swallowing and Belching

Silva

Aprile

Dantas

2015

Arq. Gastroenterol.

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-Background -Eructation is a physiologic event which allows gastric venting of swallowed air and most of the time is not perceived as a symptom. This is called gastric belching. Supragastric belching occurs when swallowed air does not reach the stomach and returns by mouth a short time after swallowing. This situation may cause discomfort, life limitations and problems in daily life. Objective -Our objective in this investigation was to evaluate if gum chewing increases the frequency of gastric and/or supragastric belches. Methods -Esophageal transit of liquid and gas was evaluated by impedance measurement in 16 patients with complaint of troublesome belching and in 15 controls. The Rome III criteria were used in the diagnosis of troublesome belching. The esophageal transit of liquid and gas was measured at 5 cm, 10 cm, 15 cm and 20 cm from the lower esophageal sphincter. The subjects were evaluated for 1 hour which was divided into three 20-minute periods: (1) while sitting for a 20-minute base period; (2) after the ingestion of yogurt (200 mL, 190 kcal), in which the subjects were evaluated while chewing or not chewing gum; (3) final 20-minute period in which the subjects then inverted the task of chewing or not chewing gum. In gastric belch, the air flowed from the stomach through the esophagus in oral direction and in supragastric belch the air entered the esophagus rapidly from proximal and was expulsed almost immediately in oral direction. Air swallows were characterized by an increase of at least 50% of basal impedance and saliva swallow by a decrease of at least 50% of basal impedance, that progress from proximal to distal esophagus. Results -In base period, air swallowing was more frequent in patients than in controls and saliva swallowing was more frequent in controls than in patients. There was no difference between the medians of controls and patients in the number of gastric belches and supragastric belches. In six patients, supragastric belches were seen at least once during the 20-minute base period. None of the controls had supragastric belches. In the control group, the ingestion of yogurt caused no significant alteration in the number of air swallows, saliva swallows, gastric belches and supragastric belches. In the patient group, there was an increase in the number of air swallows. If the subjects were chewing gum during this 20-minute period, there was an increase in the number of saliva swallows in both groups, without alterations of the number of air swallow, gastric belches and supragastric belches. There was no alteration in the number of the saliva swallows, air swallows, gastric belches and supragastric belches in both groups for subjects who did not chew gum in the 20-40 minute period after yogurt ingestion. When the subjects were chewing the gum, there was an increase in saliva swallows in the control and patients groups and in air swallows in the patients group. Conclusion -Gum chewing causes an increase in saliva swallowing in both patients with excessive belching and in co...

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“…Sendo assim, ela não requer suposições quanto a distribuição dos dados. Os resultados foram obtidos com o auxilio do software SAS ® 9.0, através da PROC NPAR1WA (13)(14)(15)(16) . A distribuição dos dados aponta claramente para um predomínio das cirurgias no horário comercial, na proporção aproximada de 5:1.…”

Section: Methodsunclassified

Correlação entre o momento da cirurgia e a ocorrência de complicações per-operatórias no tratamento das fraturas trocanterianas do fêmur

Mascarenhas¹,

Albuquerque²,

Vieira³

et al. 2011

Rev. bras. ortop.

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RESUMOObjetivo: Estabelecer se há correlação entre o momento da cirurgia e a ocorrência de complicações intra e pós-operatórias no tratamento das fraturas trocanterianas do fêmur no idoso. Método: Estudo retrospectivo avaliando o histórico de 281 pacientes operados entre 2000 e 2009 no Hospital das Clinicas da FMRP-USP. As variáveis avaliadas foram: sexo, idade, data, mecanismo do trauma, momento da admissão, tipo da fratura, complicações pré e pós-operatórias, tempo entre o trauma e a cirurgia, horário e duração da cirurgia, implante utilizado, Tip Apex Distance (TAD), tempo de hospitalização, re-operações. De acordo com o horário da cirurgia os casos foram divididos em dois grupos: Horário Comercial (7:00 -17:00) x Horário Plantão (17:01 -6:59). Resultados: Houve um predomínio de cirurgias no horário comercial, na proporção aproximada de 5:1. O intervalo de tempo médio entre a data do trauma e a cirurgia foi de três dias. Não houve diferença estatística entre os grupos (hora comercial x plantão) relacionada ao TAD médio, tipo da fratura, implante, complicações sistêmicas e mortalidade em um ano. O tempo médio entre o trauma e a cirurgia foi três dias. Conclusões: Para pacientes que são admitidos ou operados com mais de 24 horas decorridas do trauma, o horário da cirurgia não se mostrou uma variável relevante, no que diz respeito à ocorrência de complicações per operatórias. Em nossa realidade, é preferível realizar a fixação destas fraturas em horário comercial, dispondo de completa infra-estrutura de recursos humanos e técnicos.

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Estimation in generalized linear models with random effects

Cited by 1,025 publications

References 10 publications

Comparison of statistical models to analyse the genetic effect on within-litter variance in pigs

Comparison of statistical models to analyse the genetic effect on within-litter variance in pigs

Effect of Gum Chewing on Air Swallowing, Saliva Swallowing and Belching

Correlação entre o momento da cirurgia e a ocorrência de complicações per-operatórias no tratamento das fraturas trocanterianas do fêmur

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