Comparative study of anthropometric measurements of the same subjects in two different institutes.код для вставкиСкачать
Comparative Study of Anthropometric Measurements of the Same Subjects in Two Different Institutes H. C. G. KEMPER AND J. J. L. PIETERS Coronel Laboratory and Labortitory of Psychophysiology, J a n S w a m m e r d a m Institute, University of A m s t e r d a m , t h e Netherlands and Central Institute f o r Nutrition and Food Research ( C I V O , T N O ) , Zeist, t h e Netherlnnds K E Y W O R D S Comparability . Objectivity . Anthropometry Measurements. ABSTRACT The objectivity of several anthropometric measurements were tested in two institutes on the same subjects. In many cases systematic differences are to be expected: 1. Girth measurements tend to differences in the same direction. 2. The comparability of skeletal measurements is often uncertain; some measurements tend to give lower, other ones higher figures. Biacromial diameter and radio-ulnar epicondylar width do not reveal systematic differences. 3. Skinfold thicknesses measured do not reveal systematic differences. Some 50 different procedures described in Human Biology, a Guide to Field Methods (Weiner and Lourie, '69) cover a wide range of investigations essential to the biological study of human populations. By following these procedures investigators could achieve one of the major aims of the International Biological Programme (I.B.P.), a high degree of comparability between studies of different populations. All methods, even when described in great detail, demand a thorough acquaintance with their underlying principles. Even such a simple technique as anthropometry cannot give reliable results unless the observer has practiced the methods extensively (Meredith, '36; Steggerda, '42). The purpose of the present study was to test the objectivity of several routine anthropometric measurements from the recommended IBP full list (Barrow and McGee, '68). It is essential that very small differences occur between the same sets of scores measured by different investigators (Marshall, '37). The correlation coefficient of objectivity, derived from paired measurements, should be high. MET H 0DS In March 1970, 50 boys 12 and 13 years old from a secondary school in Amsterdam AM. J. PHYS. ANTHROP., 40: 341-344. (St. Ignatius College), were measured independently by experienced workers in two institutes: -Central Institute for Nutrition and Food Research (CIVO-TNO) in Zeist, and -Coronel Laboratory and Laboratory for Psychophysiology, Jan Swammerdam Institute (University of Amsterdam) in Amsterdam. The principal reason for accumulating these anthropometric data was different for each institute. Afterwards we decided to compare the two sets of data taken on the same subjects. All measurements were taken in normal conditions and not under unusually favorable ones as in the case of Marshall ('37). In each institute all measurements were taken by a team of workers previously trained according to the techniques described by Tanner ('64). There was no preliminary training to minimize the interobserver differences. All measurements were, wherever possible, taken on the left side of the body. Measurements are listed in a convenient working order: weight, stature, biacromial diameter (shoulder width), bi-iliocristal diameter (pelvic width), radio-ulnar epicondylar width (wrist breadth), femoral bicondylar width (knee breadth), upper arm circumference, thigh circumference, calf circumference, 34 1 342 H . C. G. KEMPER AND J. J. L. PIETERS tricipital-, subscapular- and supra-iliaca1 skinfold thickness. The same measuring instruments were used in both institutes (except for stature and weight): a steel measuring tape (Black and Decker) for circumferences; a sliding caliper for knee and wrist breadth; spreading caliper for shoulder and pelvic width and skinfold caliper (Harpenden) for skinfolds. In both institutes the accuracy of the instruments was checked periodically for proper scale calibration. RESULTS For each measurement the me% values of Zeist (x,) and for Amsterdam (x,) were calculated. In table 1 column (1) the mean differences and standard deviations of these data are listed (de Jonge, '64). In 9 out of 12 measurements the mean differences could not be attributed to change (,=0.05). No differences were found for biacromial diameter, subscapular- and supra-iliacal skinfolds. In table 1 column (2) the correlation coefficients of the data collected at the two institutes are given. All are high and significant at the 1% level. These figures, however, have a limited value without more information on the extent of the differences €or each measure- ment along the whole range of values of the group. Therefore we calculated also the correlation coefficient between the differences (x - x,) and the mean absolute values and summarized them in table 1 column (3). In 4 out of 12 comparisons, the coefficients are significant at a 5% level: bi-iliocristal diameter, thigh circumference, subscapular skinfold and supra-iliacal skinfold. Further analysis reveals that in subscapular skinfold differences for high values were larger than for low values and in thigh circumferences and supra-iliacal skinfold differences for high values were smaller than for low values. (v) DISCUSSION The comparison of test results involves consideration of systematic and non-systematic differences (Clarke and Clarke, '70). The data of table 1 demonstrate that 9 out of 12 anthropometric measures show systematic differences between the two laboratories: in the mean of 3 out of 12 measurements values of Amsterdam are systematically lower than those of Zeist (weight, bi-iliocristal diameter and femoral bicondylar width); it appears from the table that all three skinfolds as well as the other measurements given, are higher in Amsterdam. TABLE I Dtrtn collected i n t h e t w o i n s t i t u t e s o n the, s a m e szibjects: ( I ) M e a n differences nnd stnndnrd deviations (S.D.); ( 2 ) Coefficients of correlation ( r ) b e t w e e n x z a n d x,: (3) Coefficients of correltrtion ( r ) b e t w e e n (x, -x(,) and (2) Anthropometric measureinen t s Weight Stature Biacromial diameter Bi-iliocristal diameter Radio-ulnar epicondylar width Femoral bicondylar width Upper arm circumference Thigh circumference Calf circumference Tricipital skinfold Subscapular skinfold Supra-iliacal skinfold 1 p S 0.05. 2 pso.01. r between xz-xa Mean (S.D.) xz and x, kg cm cm cm +0.466 '(0.465) -0.624 l(0.501) -0.004 (0.603) +0.271 1 (0.355) 0.995 2 0.996 2 0.872 2 0.948 2 cm cm cm cm cm mm mm mm -0.092 l(O.192) +0.470 1 (0.355) - 1.659 1 (0.600) - 3.1 14 1 (0.929) - 1.045 1 (0.348) - 0.480 1 (1.080) - 0.046 (0.654) -0.002 (1.483) 0.903 2 0.940 2 0.971 2 0.982 2 0.992 2 0.952 2 0.973 2 0.951 2 (3) r between -xa) and (xz xz i x , 2 +0.089 - 0.039 f0.189 0.274 1 + +0.189 +0.189 - 0.148 - 0.357 1 - 0.207 - 0.058 0.395 2 - 0.306 1 + OBJECTIVITY OF ANTHROPOMETRY In as much as the instruments themselves remain constant, differences probably refer to any personal influence of the examiner. In Zeist for instance, all three circumferences were consistently lower than those in Amsterdam. When dealing with girth measurements care must be taken to exert the same tension on the ends of the tape at each reading. According to Weiner and Lourie (‘69: 7) “contact with the skin should be continuous along the tape, but the skin should not be pressed inwards.” The systematic lower values of Zeist could be explained by a difference in tightening the steel tape around the limbs. No systematic difference could be found in mean biacromial diameter. This particular skeletal measurement, however, shows a relatively low coefficient of objectivity (r = 0.87), which is an indication of poor reproducibility. Similarly the correlation coefficient for the radio-ulna epicondylar width is not as high as in others (r = 0.90). All other correlation coefficients exceed 0.90 indicating satisfactory correlation between the two institutes according to Barrow and McGee’s arbitrary standards (‘68). We have to consider, however, that for four of these measurements the differences in the low and high values between the two institutes are not equal (table 1, column ( 3 ) >. A certain amount of error, the variable error, is inevitable in the testing process no matter how much care is taken to ensure that the instruments are calibrated and the testing procedures are standardized. Such variability especially in the 343 measurement of biacromial diameter is likely. This measurement has to be taken on the subject “with his shoulder relaxed to the point of slumping forward” (Tanner, ’64: 25), resulting in a maximum shoulder width. Squaring the shoulders backward invariably decreases biacromial diameter. For the radio-ulnar epicondylar width the rotation of the lower arm may be different in separate measurements. Such an intraindividual variability of the subject in holding his shoulder more or less relaxed and his wrist more or less rotated could contribute to the rather low objectivity coefficient of biacromial diameter and radio-ulnar epicondylar width. LITERATURE CITED Barrow, H. M., and R. McGee 1968 A Practical Approach to Measurement in Physical Education. Lea and Febiger, Philadelphia. Clarke, D. H., and H. H. Clarke 1970 Research Processes in Physical Education, Recreation and Health. Prentice Hall, Englewood Cliffs, New Jersey. Jonge, H. de 1964 Inleiding tot de medische statistiek I en I1 (Introduction to medical statistics). Nederlands Instituut voor Praeventieve Geneeskunde (NIPG), Leiden. Marshall, E. L. 1937 The objectivity of anthropometric measurements taken on eight- and nine-year-old white males. Child Develop., 8: 249-256. Meredith, H. V. 1936 The reliability of anthropometric measurements taken on eight- and nine-year-old white males. Child Develop., 7: 262-2 72. Steggerda, M. 1942 Anthropometry of the living: A study on checking of techniques. Anthrop. Briefs, 2: 7-15. Tanner, J. M. 1964 The Physique of the Olympique Athlete. Allen and Unwin, London. Weiner, J . S.,and J. A. Lourie 1969 IBP Handbook, no. 9. Human Biology, a Guide to Field Methods. Blackwell, Oxford.