SOCR Data NIPS InfantVitK ShotData

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Contents

SOCR Data - SOCR Body Density Data

Summary

This is a comprehensive dataset that lists estimates of the percentage of body fat determined by underwater weighing and various body circumference measurements for 252 men.

Classroom use of this data set

Body Mass Index

This data set can be used to illustrate multiple regression techniques. Accurate measurement of body fat is inconvenient/costly and it is desirable to have easy methods of estimating body fat that are cost-effective and convenient.

References to the BMI index by country/region and per capita food consumption and undernourishment (calories) may be appropriate when discussing BMI.

Siri's Equation

A variety of popular health books suggest that the readers assess their health, at least in part, by estimating their percentage of body fat. In Bailey (1994), for instance, the reader can estimate body fat from tables using their age and various skin-fold measurements obtained by using a caliper. Other texts give predictive equations for body fat using body circumference measurements (e.g. abdominal circumference) and/or skin-fold measurements ( Behnke and Wilmore, 1974, pp. 66-67; Wilmore, 1976, p. 247; or Katch and McArdle, 1977, pp. 120-132).

Percentage of body fat for an individual can be estimated once body density has been determined. Siri (1956) assumes that the body consists of two components - lean body tissue and fat tissue.

  • Suppose we let:
    • D = Body Density (gm/cm3)
    • A = proportion of lean body tissue
    • B = proportion of fat tissue (A+B=1)
    • a = density of lean body tissue (gm/cm3)
    • b = density of fat tissue (gm/cm3)
  • Then, we have D = {1 \over {A \over a} + {B\over b}} and solving for B we find

B = {1\over D}\times{a b\over a-b} - {b\over a-b}. Using the estimates a=1.10 gm/cm3 and b=0.90 gm/cm3 ( Katch and McArdle, 1977, p. 111 or Wilmore, 1976, p. 123) we come up with Siri's equation: Percentage of Body Fat PBF = 100\times B = {495\over D} - 450.

Estimation of Body Density (BD)

Volume, and hence body density, can be accurately measured a variety of ways. The technique of underwater weighing computes body volume as the difference between body weight measured in air and weight measured during water submersion. In other words, body volume is equal to the loss of weight in water with the appropriate temperature correction for the water's density (Katch and McArdle, 1977, p. 113). Using this technique, BD = {WA\over {WA-WW\over CF} - LV}, where

  • WA = Weight in air (kg)
  • WW = Weight in water (kg)
  • CF = Water correction factor. CF=1 at 4o C (Celsius) as one-gram of water occupies exactly one cm3 of space, and CF=0.997 at 25o C)
  • LV = Residual Lung Volume (liters) Katch and McArdle (1977), p. 115.

Other methods of determining body volume are given in Behnke and Wilmore, 1974, p. 22.

BMI Calculators

There are many body-mass-index calculators. Here are some examples:

Data Description

The body density dataset includes the following 15 variables listed from left to right:

  • Density determined from underwater weighing
  • Percent body fat from Siri's (1956) equation
  • Age (years)
  • Weight (kg)
  • Height (cm)
  • Neck circumference (cm)
  • Chest circumference (cm)
  • Abdomen 2 circumference (cm)
  • Hip circumference (cm)
  • Thigh circumference (cm)
  • Knee circumference (cm)
  • Ankle circumference (cm)
  • Biceps (extended) circumference (cm)
  • Forearm circumference (cm)
  • Wrist circumference (cm)
  • Notes
    • The measurement standards are listed in Benhke and Wilmore, 1974, pp. 45-48, where, for instance, the abdomen 2 circumference is measured laterally, at the level of the iliac crests, and anteriorly, at the umbilicus.
    • These data are used to produce the predictive equations for lean body weight given in the abstract Generalized body composition prediction equation for men using simple measurement techniques, K.W. Penrose, A.G. Nelson, A.G. Fisher, FACSM, Human Performance Research Center, Brigham Young University, Provo, Utah 84602 as listed in Medicine and Science in Sports and Exercise, vol. 17, no. 2, April 1985, p. 189.
    • The predictive equations were obtained from training data (the first 143 of the 252 cases that are listed in the spreadsheet below). The remaining 109 cases may be used for testing.
    • These data were generously supplied by Dr. A. Garth Fisher who gave permission to freely distribute the data and use for non-commercial purposes.
    • The data is also available in PDF format.
    • The body-mass-index is defined by: BMI = {Weight(kg)\over Height^2(m)}.

Data Table

References

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