Christopher W. Schmidt - University of Indianapolis Archeology ...

junction between the forth premolar and the first molar (P4/M1) is given a score of “3.” Lastly,
if the mental foramen is directly beneath the first molar (M1) it is assigned a score of “4.” In
cases where multiple foramina are present, the largest foramen is scored.
Mandibular measurements. Five basic measurements are taken to account for the size
differences that may be found: bigonial width, bicondylar breadth, mandibular length,
mandibular angle, and minimum ramus breadth. Each measurement is taken with either a
Mitutoyo Sliding Calipers or a Paleo-Tech Mandibulometer, following Moore-Jansen and Jantz
(1990). A mandibulometer was not available at the Hamann-Todd collection; therefore,
mandibular length and mandibular angle could not be taken on those 350 individuals.
Statistical Analysis
This study provides simple descriptive statistics (trait frequencies) for the nominal and
ordinal traits by rank. For each bilateral trait, frequencies are given for both sides and a
combined frequency for each side is also presented. Traits that are not bilateral (chin shape and
chin prominence) have their frequencies presented for each rank.
The Wilcoxon Signed Ranks Test is a non-parametric procedure that can be used to
compare two ordinal or nominal variables. This test is used on the non-metric traits to see if
there is a relationship between trait frequency and side. The null hypothesis is that there is no
difference in bilateral trait expression.
An analysis of covariance (ANCOVA) is used for the continuous measurements. The
effects that ancestry, sex, age, and the interaction between sex and ancestry (the independent
variables) have on each measurement (the dependent variable) are measured separately.
Ancestry, sex, and their interaction are categorical independent variables, while age is a
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