Errors in Measurement of Body Composition using Generalizability Theory

초록

As the number of students with overweight is increasing, there is a growing need to examine Korean adolescents’ body composition, one of the health-related fitness components. It is very difficult for physical educators to implement the rigid measurement procedures of body composition due to limitations of instruments and budget. For this reason, it is not surprised to have errors in measuring body composition. Purpose: The purpose of this study is to identify the error sources of skinfold measurement in order to develop the standards for measuring body composition for male middle students. Methods: A generalizability theory has been often used to provide the sources of variation during the measuring process. Two hundred six male students from the middle school were involved in this study. The skinfold measurement is conducted using three composite models by three of the examiners (an expert, a semi-expert, and a non-expert) over three trials. Three calipers including hapenden caliper, lange skinfold caliper, and skindex were used. Results: This study found that about 61% of variation came from participants themselves and 38% of variation from complex interactions among examiners, participants, instruments, and trials. The measurement results are significantly different over the examiners (between the expert and the semi-expert; between the expert and the non-expert). It seems that the results of non-expert examiners are not appropriate to measure body composition. The errors of intra-examiners are very small, whereas the errors of inter-examiners are relatively big. The results from Lange skinfold caliper are more consistent than the ones of other calipers. Conclusions: It is suggested that the knowledge, skills, and training of skinfold measurements (especially landmarking techniques) are needed when accessing body composition of middle school students.