R: Risk Factors Associated with Low Infant Birth Weight

Birthwt {grpreg} | R Documentation

## 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

    data(Birthwt)

### Format

The `Birthwt` object is a list containing four elements:

- `bwt`:Birth weight in kilograms

- `low`:Indicator of birth weight less than 2.5kg

- `X`:Matrix of predictors

- `group`:Vector describing how the columns of X are grouped

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.

### Source

`MASS`. `R` package. https://cran.r-project.org/package=MASS

### 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

### See Also

`birthwt`, `grpreg`

### Examples

    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

[Package grpreg version 3.2-1 Index]