Linear regression to approximate longitudinal growth curves: revised standards for velocity of weight and length in infants.
Because of lack of acceptability of the previous log-linear model of slope velocity for the assessment of weight and length in children 1 to 36 months of age, a modified method for least squares determination of velocity of growth by slope has been designed. This model uses a compound logarithmic expression of time and a newly designed graphic scale. The acceptability of the graphic (hand-drawn) line is retained while "goodness of fit" of the model is improved. This improved model makes it possible to revise our standards for velocity of growth of children 1 to 36 months of age.