title: Statistical analysis of compositional data in anatomy.
abstract: BACKGROUND
  Variables which describe the composition, or relative size of components, of an organism need to be analysed in an appropriate manner.
  
  
  METHODS
  A few of the appropriate descriptive and inferential techniques have been described and applied to a number of anatomical data sets.
  
  
  RESULTS
  When applied to data on the composition of the vastus medialis in adults, a small but significant difference in average muscle fibre type distribution was demonstrated between males and females. There was little evidence for a relationship between fibre type distribution and age over the range considered.
  
  
  CONCLUSIONS
  Graphical displays via ternary diagrams are a simple way of illustrating compositional data simultaneously between and within groups. Numerical analysis is likely to involve transformation of original variables before standard univariate or multivariate statistical techniques can be used.
authors.affiliation: Department of Medical Statistics, University of Newcastle, United Kingdom.
authors.forename: D
authors.initials: D
authors.lastname: Howel
mesh_terms: D000328:Adult; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008433:Mathematics; D015999:Multivariate Analysis; D018485:Muscle Fibers, Skeletal / Q000145:classification*; D018482:Muscle, Skeletal / Q000033:anatomy & histology*; D012727:Sex Characteristics