\Header{birthwt}{Risk Factors Associated with Low Infant Birth Weight}
\keyword{datasets}{birthwt}
\begin{Description}\relax
The \code{birthwt} data frame has 189 rows and 10 columns.
The data were collected at Baystate Medical Center, Springfield, Mass
during 1986.
\end{Description}
\begin{Usage}
\begin{verbatim}
data(birthwt)
\end{verbatim}
\end{Usage}
\begin{Format}\relax
This data frame contains the following columns:
\describe{
\item[\code{low}] indicator of birth weight less than 2.5kg

\item[\code{age}] mother's age in years

\item[\code{lwt}] mother's weight in pounds at last menstrual period

\item[\code{race}] mother's race (\code{1} = white, \code{2} = black, \code{3} = other)

\item[\code{smoke}] smoking status during pregnancy

\item[\code{ptl}] number of previous premature labours

\item[\code{ht}] history of hypertension

\item[\code{ui}] presence of uterine irritability

\item[\code{ftv}] number of physician visits during the first trimester

\item[\code{bwt}] birth weight in grams
}
\end{Format}
\begin{Source}\relax
Hosmer, D.W. and Lemeshow, S. (1989)
\emph{Applied Logistic Regression.}
New York: Wiley
\end{Source}
\begin{References}\relax
Venables, W. N. and Ripley, B. D. (2002)
\emph{Modern Applied Statistics with S.} Fourth edition.  Springer.
\end{References}
\begin{Examples}
\begin{ExampleCode}
attach(birthwt)
race <- factor(race, labels = c("white", "black", "other"))
ptd <- factor(ptl > 0)
ftv <- factor(ftv)
levels(ftv)[-(1:2)] <- "2+"
bwt <- data.frame(low = factor(low), age, lwt, race,
    smoke = (smoke > 0), ptd, ht = (ht > 0), ui = (ui > 0), ftv)
detach("birthwt")
options(contrasts = c("contr.treatment", "contr.poly"))
glm(low ~ ., binomial, bwt)
\end{ExampleCode}
\end{Examples}

