Factor analysis of finger ridge-counts in Blacks and Whites.

Finger ridge-counts of an American White, American Black and an African Black sample were subjected to factor analysis. The analysis was carried out using correlation matrices computed from 10-ridge counts, each finger being represented by its largest count, and from 20 ridge-counts, using both radial and ulnar counts for each finger. The 20 count analysis was much more informative, demonstrating the relative independence of the radial and ulnar sides of the fingers. Moreover, the radial and ulnar counts themselves generally resulted in two factors reflecting counts on the ulnar digits and the median digits. The independence of the thumb was also demonstrated. There was considerable intersample consistency, although some evidence of sex and race variation was observed.