Extending the Box–Cox Transformation to the Linear Mixed Model

Gurka, Matthew J.; Edwards, Lloyd J.; Muller, Keith E.; Kupper, Lawrence L.

doi:10.1111/j.1467-985x.2005.00391.x

Cited by 92 publications

(113 citation statements)

References 33 publications

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“…The Box-Cox test (Box & Cox, 1964; using the function "boxcox" in the package "MASS" in R, Venables & Ripley, 2002) indicated that the reciprocal transformation of the latencies was the most appropriate transformation for the data to reduce skewness and approximate a normal distribution. The Box-Cox test is commonly used in linear mixed-effect modeling to find the most appropriate transformation function that produce normally distributed residuals (Gurka et al, 2006;Gurka et al, 2007; see also Baayen & Milin, 2010). Instead of the suggested simple reciprocal transformation (i.e., 1/RT), we used -1000/RT to facilitate the reading and interpretation of our results.…”

Section: Resultsmentioning

confidence: 99%

Reconciling phonological neighborhood effects in speech production through single trial analysis

Sadat

Martin

Costa

et al. 2014

Cognitive Psychology

117

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A crucial step for understanding how lexical knowledge is represented is to describe the relative similarity of lexical items, and how it influences language processing. Previous studies of the effects of form similarity on word production have reported conflicting results, notably within and across languages. The aim of the present study was to clarify this empirical issue to provide specific constraints for theoretical models of language production. We investigated the role of phonological neighborhood density in a large-scale picture naming experiment using finegrained statistical models. The results showed that increasing phonological neighborhood density has a detrimental effect on naming latencies, and re-analyses of independently obtained data sets provide supplementary evidence for this effect. Finally, we reviewed a large body of evidence concerning phonological neighborhood density effects in word production, and discussed the occurrence of facilitatory and inhibitory effects in accuracy measures. The overall pattern shows that phonological neighborhood generates two opposite forces, one facilitatory and one inhibitory. In cases where speech production is disrupted (e.g. certain aphasic symptoms), the facilitatory component may emerge, but inhibitory processes dominate in efficient naming by healthy speakers. These findings are difficult to accommodate in terms of monitoring processes, but can be explained within interactive activation accounts combining phonological facilitation and lexical competition. 2Reconciling phonological neighborhood effects in speech production through single trial analysis Native speakers of a language know a myriad of different words. This so-called mental lexicon is often described as an interconnected network in which representation distance may depend on meaning or form similarities among the words. One crucial step for understanding this network is to describe which kind of similarity influences language processing and how it modulates performance. In this context, the current research is concerned with the role of phonological similarity in word retrieval and speech production. This issue has been addressed in earlier theoretical work (e.g. Chen & Mirman, 2012;Dell & Gordon, 2003), but the empirical evidence on which this work is grounded remains controversial. Our goal in this article is to clarify the empirical facts regarding form similarity effects in speech production, and to integrate them within a single account. Clearing the empirical constraints will allow further refinement of theoretical models to advance our understanding of the cognitive processes underlying speech production.An approximation of how similar or interconnected a word is within the lexical network can be obtained by computing its phonological neighborhood density (PhND). PhND refers to the number of words that can be formed from a given word by substituting, adding or deleting one phoneme (Luce, 1986). For example, the word "bat" sounds similar to many other words (e.g., "cat", "fat",...

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Section: Resultsmentioning

confidence: 99%

Reconciling phonological neighborhood effects in speech production through single trial analysis

Sadat

Martin

Costa

et al. 2014

Cognitive Psychology

117

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“…Because the use of maximum likelihood estimation methods in mixed linear modelling assumes that the dependent variable is normal, the distributions of all variables were reviewed. Box-Cox transformations were applied to energy and all nutrient variables to ensure that they approximated normal distributions (51) , and mixed linear models were run using the Residual Maximum Likelihood estimation method (REML). Although the servings of vegetables and fruits in meals appeared normal without transformation, the distributions of servings from the other food groups were skewed and could not be transformed to approximate normality.…”

Section: Effect Of Food Donationsmentioning

confidence: 99%

Nutritional assessment of charitable meal programmes serving homeless people in Toronto

Tse

Tarasuk

2008

Public Health Nutr.

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“…The choice of the scaling parameter was driven by the need to make the output data as normally distributed and homoscedastic as possible. In order to ensure this, we adopted a REML-based approach devised by Gurka et al (2006). However, applying the inverse transformation to the transformed model results in biased estimates of the mean, but not the median, on the original scale (Duan, 1983), so we present medians in subsequent analyses.…”

Section: Methodsmentioning

confidence: 99%

Modeling Fetal Weight for Gestational Age: A Comparison of a Flexible Multi-level Spline-based Model with Other Approaches

Villandré¹,

Hutcheon²,

Trejo³

et al. 2011

The International Journal of Biostatistics

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We present a model for longitudinal measures of fetal weight as a function of gestational age. We use a linear mixed model, with a Box-Cox transformation of fetal weight values, and restricted cubic splines, in order to flexibly but parsimoniously model median fetal weight. We systematically compare our model to other proposed approaches. All proposed methods are shown to yield similar median estimates, as evidenced by overlapping pointwise confidence bands, except after 40 completed weeks, where our method seems to produce estimates more consistent with observed data. Sex-based stratification affects the estimates of the random effects variancecovariance structure, without significantly changing sex-specific fitted median values. We illustrate the benefits of including sex-gestational age interaction terms in the model over stratification. The comparison leads to the conclusion that the selection of a model for fetal weight for gestational age can be based on the specific goals and configuration of a given study without affecting the precision or value of median estimates for most gestational ages of interest.

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Extending the Box–Cox Transformation to the Linear Mixed Model

Cited by 92 publications

References 33 publications

Reconciling phonological neighborhood effects in speech production through single trial analysis

Reconciling phonological neighborhood effects in speech production through single trial analysis

Nutritional assessment of charitable meal programmes serving homeless people in Toronto

Modeling Fetal Weight for Gestational Age: A Comparison of a Flexible Multi-level Spline-based Model with Other Approaches

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