The significance of the correlation coefficient when applied to Mendelian distributions / by John Brownlee.

  • Brownlee, John, 1868-1927.
Date:
1910
Catalogue details

Licence: In copyright

Credit: The significance of the correlation coefficient when applied to Mendelian distributions / by John Brownlee. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    Parent. Offspring. (a, a) + (a, b). (b, b). Totals. (a, a) + (a, b) 5 1 6 (b, b) . ] 1 2 Totals 6 2 8 Here again the regression is linear, and as the result we have o o •333. So far all is clear. In the last case, however, the distribution is markedly skew, and while the product method is applicable it is only applicable because the regression is linear. 7. It is therefore specially important to consider what happens when other methods of obtaining the correlation are employed. The chief of these is the fourfold division method. In a Mendelian instance such as this, the fourfold table seems specially applicable, but it assumes normality of distribution so that the fourfold table should give a higher correlation than r=-3333. As a matter of fact it does. The equation for determining r is •62035 =r+‘22747r2 + -04951r3+-12279^ +-001898r5+ . . . which gives r = - 53. That is to say, the correlation is even higher than that obtained when the hybrid is distinguishable from the dominant, and in applying the fourfold method we have returned to or even gone beyond the uncondensed table. The higher coefficients are likewise increased and the series becomes Parental. Grand- Great- Great-great- parental. grandparental. grandparental, •53, •29, •15, and -073 as against •5, •25, T25, and -063. 8. If the simple Mendelian table be again considered, and if for the moment the distinguishing character of the hybrid and the dominant be assumed somewhat indefinite, we can make several tentative divisions, either bisecting the hybrid or dividing it into such divisions that one- fourth resembles the recessive as follows :—