A statistical comparison of three sets of normative data from which to derive standards for craniofacial measurement

The present investigation was performed to test statistically for differences between cephalometric measurements taken from three different populations. The samples tested were broken down for age and sex and selected at random from Manchester, England; Nymegen, Holland; and Michigan, North America. The means of some of the cephalometric measurements of the different samples showed statistically significant differences reflecting underlying differences in the populations from which they were drawn. The greatest differences were observed between the Manchester and Nymegen groups (10 skeletal and 9 dental). The Nymegen group was skeletal Class II relative to the Manchester group and had a higher lower incisor angle. The next greatest differences was between the Nymegen and Michigan groups (6 skeletal and 12 dental) and the least difference between the Manchester and Michigan groups (3 skeletal and 8 dental). The only consistent difference was the greater upper incisor angle in the Michigan group in both instances. The Manchester and Michigan groups were closer to each other than either were to the Nymegen group.