be the case?
The amount of variability is most conveniently measured by a coefficient known as the standard deviation σ, which is small when the range of variation is small, but large when diversity of material is great. The following comparisons of the point at issue may be made.85
| Avg. | σ | ||
|---|---|---|---|
| 100 | American men | 78.3 | 3.1 |
| 1011 | Cambridge graduates (English males) | 79.85 | 2.95 |
For the men, little difference is discernible. The Old Americans are slightly more long-headed than the English, but the amount of variation in this trait is nearly the same on the two sides of the ocean.
The average of the American women is 79.5 with σ = 2.6. No suitable series of English women has been found for comparison.86 It will be noted that the American women are slightly more round-headed than the men; this is found regularly to be the case, when comparisons of the head form of the two sexes are made in any race.
In addition to