abdom {lmls}

Abdominal circumference data

Description

The abdom data frame has 610 rows and 2 columns. The data are measurements of abdominal circumference (response variable) taken from fetuses during ultrasound scans at Kings College Hospital, London, at gestational ages (explanatory variable) ranging between 12 and 42 weeks.

Usage

data(abdom)

Format

This data frame contains the following columns:

y

Abdominal circumference: a numeric vector.

x

Gestational age: a numeric vector.

Details

The data were used to derive reference intervals by Chitty et al. (1994) and also for comparing different reference centile methods by Wright and Royston (1997), who also commented that the distribution of z-scores obtained from the different fitted models "has somewhat longer tails than the normal distribution".

Source

Dr. Eileen M. Wright, Department of Medical Statistics and Evaluation, Royal Postgraduate Medical School, Du Cane Road, London, W12 0NN.

The abdom dataset was copied into the lmls package from the gamlss.data package. gamlss.data is licensed under the GPL 2 and 3.

References

Chitty, L.S., Altman, D.G., Henderson, A. and Campbell, S. (1994). Charts of fetal size: 3, abdominal measurement. Br. J. Obstet. Gynaec., 101: 125–131.

Wright, E.M. and Royston, P. (1997). A comparison of statistical methods for age-related reference intervals. J. R. Statist. Soc. A., 160: 47–69.

Examples

data(abdom)
attach(abdom)
plot(x, y)
detach(abdom)