Abstract:
We propose an approach to the computation of age-related reference ranges which guarantees
that the proportion of sampled data points covered by the reference band has an arbitrarily
specified value. Unlike other approaches in the literature, this method does not have
to rely on parametric distributional assumptions. The boundaries of the bands are
given by smooth curves, and for modeling the mean as a function of age, a sufficiently
flexible class of monotonically increasing functions is used, since in the applications
all measured variables are biological growth parameters. The width of the reference
band is allowed to be proportional to any suitably fixed function of age which we
propose in practice to be taken linear. The approach is illustrated by examples from
a large-scale study of the distribution of fetal size measurements obtained by routine
prenatal sonography.
Keywords:
Band Width - Fetal Size - Regression Functions - Prenatal Sonography
