vii.] DISCUSSION OF THE DATA OF STATURE. 93

series in question refers to R.F.F. brothers, who, owing to the principle on which the Table is constructed, are only a comparatively small sample taken out of the R.F.F. Population, and on a principle that gave greater weight to a few large families than to all the rest. Therefore it could not be expected to give rise to so regular a Scheme for the general R.F.F. Population as Table 11, which was fairly based upon the whole of it. Less accuracy was undoubtedly to have been expected in this group than in either of the others.

Variability of the Population.-The value of Q in the Statures of the general Population is to be deduced from the bottom lines of any one of the Tables 11, 12, and 13. The three values of it that I so obtain, are 1.65, 11, and 1.7 inch. I should mention that the method of the treatment originally adopted, happened also to make the first of these values 1.7 inch, so I have no hesitation in accepting 1.7 as the value for all my data.

Variability of Mid-Parents.-The value of Q in a Scheme drawn from the Statures of the R.F.F. MidParents according to the data in Table 11, is 1.19 inches. Now it has already been shown that if marriage selection is independent of stature, the value of Q in the Scheme of Mid-parental Statures would be equal to its value in that of the general Population (which we have just seen to be 1.7 inch), divided by the square root of 2 ; that is by 1.45. This calculation makes it to be