Distributional shape of nutrition data.
Nutrition data from 111 undergraduate college students (51 males and 60 females, ranging in age from 17 to 24) were studied with respect to the shape of the underlying probability distributions. Three-day averages for total energy, percent protein, percent saturated fat, percent unsaturated fat, percent complex carbohydrates, percent refined carbohydrates, cholesterol, sodium, vitamin C, and iron (measured in milligrams) were computed, and their distributions were compared with the normal (Gaussian) distribution. The distribution of values of sodium for females and, to a lesser extent, cholesterol for females and of cholesterol and vitamin C for males, differed from the normal distribution. The remaining distributions appeared to be reasonably close to normal in shape. It is recommended that nutrition researchers verify the normal distribution assumptions prior to applying parametric techniques to their data and that they use nonparametric (distribution-free) techniques to analyze their data whenever those assumptions are not valid.
Emrich
L J
LJ
Department of Biomathematics, Roswell Park Memorial Institute, Buffalo, New York 14263.
Dennison
D
D
Dennison
K F
KF
D000293:Adolescent; D000328:Adult; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D008297:Male; D009749:Nutrition Surveys