Birthwt: Risk Factors Associated with Low Infant Birth Weight

Description

The Birthwt data contains 189 observations, 16 predictors, and an outcome, birthweight, available both as a continuous measure and a binary indicator for low birth weight.The data were collected at Baystate Medical Center, Springfield, Mass during 1986. This data frame is a reparameterization of the birthwt data frame from the MASS package.

Usage

Birthwt

Arguments

Format

The Birthwt object is a list containing four elements (X, bwt, low, and group):

bwt: Birth weight in kilograms
low: Indicator of birth weight less than 2.5kg
group: Vector describing how the columns of X are grouped
X: A matrix with 189 observations (rows) and 16 predictor variables (columns).

The matrix X contains the following columns:

age1,age2,age3: Orthogonal polynomials of first, second, and third degree representing mother's age in years
lwt1,lwt2,lwt3: Orthogonal polynomials of first, second, and third degree representing mother's weight in pounds at last menstrual period
white,black: Indicator functions for mother's race; "other" is reference group
smoke: Smoking status during pregnancy
ptl1,ptl2m: Indicator functions for one or for two or more previous premature labors, respectively. No previous premature labors is the reference category.
ht: History of hypertension
ui: Presence of uterine irritability
ftv1,ftv2,ftv3m: Indicator functions for one, for two, or for three or more physician visits during the first trimester, respectively. No visits is the reference category.

References

Venables, W. N. and Ripley, B. D. (2002). Modern Applied Statistics with S. Fourth edition. Springer.
Hosmer, D.W. and Lemeshow, S. (1989) Applied Logistic Regression. New York: Wiley

Examples

Run this code

data(Birthwt)
hist(Birthwt$bwt, xlab="Child's birth weight", main="")
table(Birthwt$low)
## See examples in ?birthwt (MASS package)
##   for more about the data set
## See examples in ?grpreg for use of this data set
##   with group penalized regression models