birthwt: Risk Factors Associated with Low Infant Birth Weight

Description Usage Format Source References Examples

Description

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

Usage

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Format

This data frame contains the following columns:

low

indicator of birth weight less than 2.5 kg.

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

References

Venables, W. N. and Ripley, B. D. (2002) Modern Applied Statistics with S. Fourth edition. Springer.

Examples

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bwt <- with(birthwt, {
race <- factor(race, labels = c("white", "black", "other"))
ptd <- factor(ptl > 0)
ftv <- factor(ftv)
levels(ftv)[-(1:2)] <- "2+"
data.frame(low = factor(low), age, lwt, race, smoke = (smoke > 0),
           ptd, ht = (ht > 0), ui = (ui > 0), ftv)
})
options(contrasts = c("contr.treatment", "contr.poly"))
glm(low ~ ., binomial, bwt)

Example output

Call:  glm(formula = low ~ ., family = binomial, data = bwt)

Coefficients:
(Intercept)          age          lwt    raceblack    raceother    smokeTRUE  
    0.82302     -0.03723     -0.01565      1.19241      0.74068      0.75553  
    ptdTRUE       htTRUE       uiTRUE         ftv1        ftv2+  
    1.34376      1.91317      0.68020     -0.43638      0.17901  

Degrees of Freedom: 188 Total (i.e. Null);  178 Residual
Null Deviance:	    234.7 
Residual Deviance: 195.5 	AIC: 217.5

MASS documentation built on April 30, 2018, 9:03 a.m.

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