Understanding Histograms   

Information taken from the  Yocom-McColl  http://www.ymccoll.com/  web site   They do our fiber testing and have been in the fiber testing business since 1964

 To analyze the micron test report histogram, find the Average Fiber Diameter (AFD) on the horizontal scale showing fiber diameter in microns. Standard Deviation is a term representing an average of individual deviations (plus or minus micron values) from the mean or AFD. The smaller the Standard Deviation, the more uniform the population of fibers measured. It is the most stable of variability measures and is used in the computation of other fiber statistics such as the Coefficient of Variation (CV).

    The Coefficient of Variation is the Standard Deviation divided by the Average Fiber Diameter multipled by 100 and reported as a percentage. The CV is used in the statistical analysis of different populations of fiber (different animals).

    The percentage of fiber greater than 30 microns is also included in the report. In commercial application and breed selection, this data is of interest because it shows the coarse edge that determines the final use of the fiber. It has a relationship to the strength of the yarn processed from the raw fiber and influences "prickle" factor, the scratchy quality associated with coarser fibers.