The Statistical Analysis of Compositional Data

Aitchison, J.

doi:10.1111/j.2517-6161.1982.tb01195.x

Cited by 2,370 publications

(2,641 citation statements)

References 45 publications

Supporting

Mentioning

2,446

Contrasting

Unclassified

Order By: Relevance

“…Afterwards, a multiple linear regression was done using the stepwise method to determine if the explanatory variables measured (growth ring characteristics, mechanical, and physical properties) were good predictors of the weighted mean chip thickness. A multivariate analysis of variance (MANOVA) was performed using the Aitchison approach of compositional data (Aitchison 1982) for the Domtar and Williams chip class distributions. Growth ring characteristics, mechanical, and physical properties were used as covariates, keeping only the ones that were significant for the model.…”

Section: Statistical Analysesmentioning

confidence: 99%

Effects of the cutting pattern and log provenance on size distribution of black spruce chips produced by a chipper-canter

2015

View full text Add to dashboard Cite

Chips of black spruce (Picea mariana (Mill.) B.S.P.) logs coming from two provenances, Montmorency (at 47°N) and Chibougamau (at 50°N) sites, were produced by a chipper-canter using three cutting widths (12.7, 19.1, and 25.4 mm). Chip dimensions were assessed by thickness, width, and length (Domtar and Williams classifications). Earlywood density, latewood density, ring density, ring width, rings per mm (R/mm), shear, splitting, modulus of elasticity (MOE), modulus of rupture (MOR) in bending, and basic density (BD) were evaluated on samples obtained within each cutting width area. The results showed that these wood attributes were significantly different between sites or/and cutting widths (12.7 and 25.4 mm). The weighted mean chip thickness (WCT) and chip class distributions (Domtar and Williams) were significantly affected by site and cutting width (CW). WCT increased as cutting width increased and its value was higher at Montmorency than at Chibougamau. The differences in WCT could be associated with the variation of growth ring characteristics, mechanical properties, and BD between sites. Moreover, chip thickness (Domtar) was significantly affected by MOR and BD while chip width and length (Williams) were significantly influenced by R/mm, BD, MOR, and shear. The analyses showed the importance of growth ring characteristics, mechanical properties, and basic density on the chip size variation. Multiple linear regressions showed that CW, MOR, BD, and R/mm were the variables that better described the variation in WCT. Chip dimensions can hence be adjusted as a function of CW but they could vary depending on the provenance of the wood and their specific attributes.

show abstract

Section: Statistical Analysesmentioning

confidence: 99%

Effects of the cutting pattern and log provenance on size distribution of black spruce chips produced by a chipper-canter

2015

View full text Add to dashboard Cite

show abstract

“…For example, the fact that a species consumes two-thirds insects constrains its seed consumption to be less than or equal to one-third. Special transformations are needed to account for this non-independence (Aitchison 1982). We used the "rcomp" function in the "compositions" package in R (v.2.6.0) to run a compositional principal components analysis (PCA).…”

Section: Diet Classiwcationmentioning

confidence: 99%

Serum antioxidant levels in wild birds vary in relation to diet, season, life history strategy, and species

2009

View full text Add to dashboard Cite

Micronutrient antioxidants are thought to be generally important for health in many animals, but factors determining levels in individuals and species are not well understood. Diet and season are obvious environmental variables that might predict the degree to which species can accumulate such nutrients. We analyzed antioxidant levels [Trolox-equivalent antioxidant capacity (TEAC), uric acid (UA), vitamin E, and four carotenoids] in 95 bird species and compared these to species-level data on diet from the literature. Using compositional principal components analysis, we identified two main axes of diet variation: invertebrate consumption and seed-to-fruit ratio. We then examined associations between diet axes and antioxidant measures, with and without control for life-history variation and phylogeny. We also analyzed a subset of 13 species for which we had data on seasonality of antioxidant levels and diet, assessing the variance in antioxidant levels explained by seasonality, diet, and species. Unsurprisingly, there were strong associations between antioxidant levels and diet. TEAC and UA concentration were consistently positively associated with invertebrate consumption and seed-to-fruit ratio, and carotenoid concentrations (e.g. zeaxanthin and beta-carotene) were negatively associated with invertebrate consumption. However, vitamin E was not associated with diet as measured here. Importantly, there is much variation in antioxidants that is not explained by diet, and we are able to identify diet-independent effects of species, season/breeding stage, and life history on antioxidant levels. Circulating antioxidant concentrations within and across species can therefore be viewed as a function of multiple factors, including but not limited to diet, and antioxidant metabolism appears to differ across species and seasons irrespective of diet.

show abstract

“…All variables were arcsine transformed and only three of six possible behaviors were used in the analysis. This reduced potential problems of dependence between behavior categories (Aitchison 1982). The behavior of the control fish was included as an additional independent variable in these analyses.…”

Section: Removal Experimentsmentioning

confidence: 99%

The costs and benefits of territory sharing for the Caribbean coral reef fish, Scarus iserti

Clifton

1990

Behav Ecol Sociobiol

View full text Add to dashboard Cite

The Statistical Analysis of Compositional Data

Cited by 2,370 publications

References 45 publications

Effects of the cutting pattern and log provenance on size distribution of black spruce chips produced by a chipper-canter

Effects of the cutting pattern and log provenance on size distribution of black spruce chips produced by a chipper-canter

Serum antioxidant levels in wild birds vary in relation to diet, season, life history strategy, and species

The costs and benefits of territory sharing for the Caribbean coral reef fish, Scarus iserti

Contact Info

Product

Resources

About