Figure 3

Variability of grey level values at different levels of the sampling hierarchy. Grey level values on each of three sections per rat are plotted. Values on the same section (left and right side) are plotted with the same symbol, and different sections are plotted with different symbols. Rats are sorted top to bottom from highest to lowest mean GL value, which allows the variability between rats to be compared to the variability within rats. The variance components analysis calculates the amount of variability at each level of the sampling hierarchy. The line method had the lowest amount of variability within and between sections and therefore the greatest variability was between rats, that is, it gave the most consistent results for multiple measurements on the same rat.