判別関数による現代日本人頭骨の性別判定法

Reliability of sexing from skulls by the discriminant function method is limited to a relatively low level in comparison with that from the extremity bones (Pons, 1955; Hanihara, 1958, 59 ; Giles and Elliot, 1963). For instance, Hanihara (1959) reported 0.856-0.897 of reliability using the Japanese skulls, and Giles and Elliot (1963) obtained 0.835-0.876 of reliability from the Caucasian and American Negro skulls. In this article, the authors tried to find more reliable discriminant functions on the skulls by increasing the number of measuring items. At the same time, the so-called stepwise method was employed to obtain the highest reliability by the smallest number of items. The materials used were 42 male and 37 female skulls from the Kanto provinces (Tokyo and the neighboring areas) whose ages were 20 through 60. The measuring items (table 1) were selected on the basis of the following rules: 1) They must be commonly used in the field of anthropology; 2) They must be easy to measure technically so that the discrepancy between investigators is negligibly small ; 3) The measurements on the part which is easy to break, or those changeable with age must be excluded. In case of the full items were included, we obtained 0.9494 of reliability, or 0.0506 of rate of error, which is considerably higher level than those obtained by the other authors (table 3). The discrimiant function coefficients for the other combinations were also computed (table 4). In these cases, however, the reliabilities are of almost the same level as those obtained by Hanihara and Giles and Elliot. Finally, the discriminant function coefficients were computed by the stepwise method using the SPSS subprogram DISCRIMINANT. In this case, 9 measuring items were included theoretically as shown in table 5, and reliability of 0.9367 was obtained. This is again higher than those obtained by the other authors, so that our initial aim to obtain the highest reliability by the smallest number of items was attained