On the subnormal variance in the counts of randomly distributed particles: I. Approximate treatment of the three-dimensional case and discussion of experiments
- 27 Downloads
The question is raised concerning the possible causes of abnormally small standard deviations found in counting samples in which particles are distributed at random (e.g., blood cells, fat globules in milk, etc.). The effect of discarding abnormal samples is discounted inasmuch as small standard deviations occur even when all samples are counted. An approximation method is used to calculate the effect of finite particle size, of known repulsive forces between particles and of convection currents. This calculation shows that neither finite size nor the known repulsive forces are sufficient to account for the observed abnormality of standard deviation, but that convection currents can possibly account for it. The possible presence of long-range repulsive forces cannot, however, be excluded.
KeywordsRepulsive Force Small Standard Deviation Counting Chamber Convection Current Abnormal Sample
Unable to display preview. Download preview PDF.
- Bergson, J., J. B. Magath, and M. Burn. 1940. “The Error of Estimate of the Blood Cell Count as Made with the Haemocytometer.”Amer. Jour. Physiol.,128, 309–23.Google Scholar
- Fisher, R. A. 1950.Contribution to Mathematical Statistics. New York: John Wiley and Sons.Google Scholar
- Kreveld, A. van. 1938. “De microscopische bacterietelling in melk.”Genootschap t. bevordering v.d. melkkunde, 2–16.Google Scholar
- —. 1942. “Regularity of the Arrangement of Fat Globules in Milk, and the Size Distribution of Fat Globules in Milk.”Rec. trav. chim. d. Pays Bas,61, 29–41, 41–53.Google Scholar
- —. 1946. “Repulsive Forces between Milk-fat Globules.”Ibid.,,65, 321–28.Google Scholar
- Verwey, E. J. W. and J. Th. G. Overbeek. 1948.Theory of the Stability of Lyophobic Colloids. Amsterdam and New York: Elsevier.Google Scholar