Graphical Analyses
I think what you are looking for are equations of the type used widely in the geosciences for extracting information from plotted distributions. Some references are:
Folk, R.L., and W.C. Ward, 1957, Brazos River Bar: A Study of the Significance of Grain-Size Parameters; J. Sediment. Petrology, 27:3-26.
Krumbein, W. C., Size-frequency distributions of sediments and the normal phi curve, J. Sed. Pet., 8, 84-90, 1983.
Robert E. Carver (edt.), 1971: Procedures in sedimentary petrology. Wiley-Interscience, A division of John Wiley and Sons, Inc., New York, London, Tokyo, 653 pp. ISBN 47113855 X.
Chapter 6 (pages 109-127): Mathematical Treatment of Size Distribution Data by Early F.McBride, University of Texas at Austin, Texas, US
Examples of these types of equations can be found at
http://www.cs.pdx.edu/~ian/geology2.5.html ■
Describing the breadth of a particle size distribution
I am looking for simple mathematical expressions for describing the spread or breadth of a particle size distribution. An example of what I am looking for is the "mid-fifty-breadth-ratio." (For the definition of this ratio, please see http://www.erpt.org/014Q/nelsa-06.htm). I would like to find other simple ways of describing a size distribution similar to the ratio mentioned above (in that it can be easily calculated). Any advice? Thanks in advance. ■