Аннотация:In our study, we have compared different methods of calculation of the degree of gender dimorphism. We chose four different indices from the most frequently used ones in works aimed at investigation of gender dimorphism. Two of them, the coefficient of gender dimorphism (GDC) and t-criterion, are similar to each other and based on the ratio of the difference of mean values and dispersions of parameters. These two parameters differ only in dependence of the t-criterion on the sample size. Two other parameters (D-index and Kolmogorov-Smirnov criterion (K-S)) are based on the calculation of the maximal difference between the distribution curves of the parameters. At that, the D-index is based on the theoretical model of distribution, and the K-S criterion uses empirical data. In the majority of studies, gender dimorphism assessment is performed using the D index and t-criterion. That is why in our study the task was to assess effectiveness of the most frequently used parameters of gender dimorphism.
A sample from native Belarussian population described in the 1970-s served as study material. The data were accumulated in accordance with the complex anthropometric program including 36 parameters. During the analysis, we distributed all examined subjects in age groups: the youngest ‒ from 18 to 34 years old (N=1148), middle-aged ‒ from 35 to 54 years old (N=1482) and senior ‒ from 55 years old (N=425). Parameters maximally informative in terms of description of gender differences were marked out for assessment of different methods of calculation of gender dimorphism using the canonical discriminant analysis. For comparison of different ways of calculation of gender dimorphism all four indices were calculated for separated parameters in each age-specific category.
Pictures 1 and 2 illustrate differences in calculation of the K-S and D parameters for signs characterizing different body components.
The lack of age-specific differences in the degree of gender dimorphism among parameters related with development of the skeleton has been shown by all assessment methods except for the t-criterion. A possible explanation is that t-criterion values depend on the sample size, so the comparison of groups with different sizes using this criterion is not possible. All assessment methods have demonstrated age-dependent increase of the degree of gender dimorphism in case of circumferential parameters. The most prominent differences in the degree of gender dimorphism between age-specific cohorts have been revealed on signs connected with adipopexis. The degree of gender dimorphism on these parameters increases significantly in the senior group. This tendency is apparent at use of two criteria – the GDC and K-S. These signs are very specific in terms of reflection of empirical differences in adipopexis, taking in account the lack of compliance with the normal distribution.
Based on the results of the performed work, the following conclusions can be made:
1. The GDC and K-S criterion demonstrate high intercorrelation reflecting changes of the degree of gender dimorphism for all parameters and ages;
2. The t-criterion is different from the GDC criterion by the multiplication factor connected with the sample size, and it is not suitable for comparison of groups different in number of subjects;
3. The D-criterion coincides with the K-S criterion in case if the distribution curve is well adjusted. However, in case the curve of theoretical distribution is incorrect, a calculated value of the D-criterion does not correspond to empirical data.
4. Among all studied ways of calculation, the most universal parameters of gender dimorphism are the GDC and K-S.