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Statistical control in haematology

Published online by Cambridge University Press:  15 May 2009

H. O. Lancaster
H. O. Lancaster
Affiliation:
From the School of Public Health and Tropical Medicine, Sydney
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The value of ‘Statistical control’ in haematology has been demonstrated. After a short historical survey of the chief contributions to the theory of the technique of counting and of the application of the Poisson distribution in biology, the statistical theory of the distribution of cells in the haemocytometer is briefly described and examples are given of large sample methods of testing goodness of fit. Some of the author's counts are considered.

In the red cell counts a ‘crowding’ effect is noted by which the variance between the counts on the individual squares on the haemocytometer is reduced. This effect is trivial in white cell counting owing to the small proportion of the area occupied, but is important in reducing the variance between the numbers of red cells on individual small haemocytometer squares. A quadratic function adequately describes the regression of the variance on the mean for fixed size of haemocytometer square, for the usual range of red cell density. This function, calculated on the basis of the author's own counts also describes Berkson's findings on crowding adequately and is not, considering the approximations involved, inconsistent with the theoretical discussion on crowding. Reasons are given for believing that the crowding effect is only trivial if blocks of 16 squares are compared in red cell counting.

The methods of statistical control, suggested by R. A. Fisher's work, are introduced. It is shown that they give satisfactory results when applied to some of the author's own counts. The methods are used to discuss the consistency of the counts of certain medical graduates and technicians. The methods are suitable for a review of the literature with the object of examining the internal consistency of the counts made by various authors.

Type
Research Article
Information
Journal of Hygiene , Volume 48 , Issue 4 , December 1950 , pp. 402 - 417
Copyright
Copyright © Cambridge University Press 1950

References

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