Heredity in the light of recent research / by the late L. Doncaster.

  • Doncaster, L. (Leonard), 1877-1920.
Date:
1921
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Heredity in the light of recent research / by the late L. Doncaster. Source: Wellcome Collection.

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    П] VARIATION II frequent heights were 67 and 69 inches, and that the more the stature differed from 68 inches in either direction, the fewer would be the men having that measurement. This could be represented graphically by arranging vertical lines representing the heights of every man in order of their height; a line joining their tops would then rise rapidly at the lower end, would be nearly flat as it passed over the men having heights near the ' modal value ' of 68 inches, and would rise again steeply to the exceptionally tall men at the upper end of the row (fig. 1). [13]^ A more instructive method of graphically repre¬ senting the distribution of variation is to take á base¬ line and divide it into equal parts, each representing an equal increment in the structure measured. From each division of the base-line a vertical line is drawn representing by its length the number of individuals having that measurement. In the imaginary case taken above, the base-line would have 17 divisions representing successive heights of from 60 to 76 inches; at each division a vertical line is drawn which by its length repre¬ sents the percentage of the population which have that height (fig. 2). By joining the tops of the per- pendiculai^s (ordinates) a curve, or more strictly a polygon, is obtained which graphically represents the 1 For references see the end of the Volume,