On collagen fibril diameter distributions.

Distributions of collagen fibril diameters, measured from electron micrographs, are compared using some of the common measures of the mean of the distribution. The role of mixture distributions in modelling these distributions is considered and a method of fitting such distributions to data observed in the form of histograms is described. The method is illustrated with six pairs of fibril diameter distributions used in assessing age and structural changes in various collagen samples from different species of animal. The extent of changes in diameter distributions is assessed in terms of the estimated means, variances and mixing proportions for the component distributions of the histograms in each pair.