The development of skinfold (anthropometric) measurements came as the result of investigations for simpler and less expensive methods of estimating body composition. Body circumferences and/or skinfold thickness are used in a regression equation, of which there are many available, for prediction of body composition. Among the most commonly employed are the generalized equations for use with skinfold measurements developed for adult males and females by Jackson and Pollock (1978) and Jackson, Pollock, and Ward (1980), respectively. They are termed generalized because they are most accurate in predicting body composition of people with average amounts of body fat. Generalized equations tend to be less accurate with the very lean (e.g. athletes), obese, young old, or other special populations. Other, more appropriate, equations have been developed for such populations which increase their accuracy for prediction of body composition.
The major source of error in anthropometry lies in the actual skinfold measurement. Making accurate skinfold measurements is more than simply pinching the skin somewhere around a particular area and measuring the thickness. There are precise sites on which the measurements are to be taken. A well-trained technician can obtain results that approach the precision of underwater weighing. Unfortunately, most people who take skinfold measurements are not well trained. Obtaining consistently accurate skinfold measurements requires training and experience.
To take a skin-fold measurement, first determine the correct measurement site. Grab the skin with the thumb and forefinger about 0.5 inch from the measurement site following the natural fold of the skin. Lift the skin up from the muscle, apply the calipers and wait for 4 seconds before reading the calipers. Fat is compressible, so reading the scale before or after the 4-sec delay may affect the results.