birthwt {MASS} | R Documentation

## Risk Factors Associated with Low Infant Birth Weight

### Description

The `birthwt` data frame has 189 rows and 10 columns. The data were collected at Baystate Medical Center, Springfield, Mass during 1986.

### Usage

    data(birthwt)

### Format

This data frame contains the following columns:

`low`
  indicator of birth weight less than 2.5kg
`age`
  mother's age in years
`lwt`
  mother's weight in pounds at last menstrual period
`race`
  mother's race (`1` = white, `2` = black, `3` = other)
`smoke`
  smoking status during pregnancy
`ptl`
  number of previous premature labours
`ht`
  history of hypertension
`ui`
  presence of uterine irritability
`ftv`
  number of physician visits during the first trimester
`bwt`
  birth weight in grams

### Source

Hosmer, D.W. and Lemeshow, S. (1989) Applied Logistic Regression. New York: Wiley

### Examples

    data(birthwt)
    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)