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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><title>R: Risk Factors Associated with Low Infant Birth Weight</title> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <link rel="stylesheet" type="text/css" href="R.css" /> </head><body> <table width="100%" summary="page for birthwt {MASS}"><tr><td>birthwt {MASS}</td><td style="text-align: right;">R Documentation</td></tr></table> <h2> Risk Factors Associated with Low Infant Birth Weight </h2> <h3>Description</h3> <p>The <code>birthwt</code> data frame has 189 rows and 10 columns. The data were collected at Baystate Medical Center, Springfield, Mass during 1986. </p> <h3>Usage</h3> <pre> birthwt </pre> <h3>Format</h3> <p>This data frame contains the following columns: </p> <dl> <dt><code>low</code></dt><dd><p>indicator of birth weight less than 2.5 kg.</p> </dd> <dt><code>age</code></dt><dd><p>mother's age in years.</p> </dd> <dt><code>lwt</code></dt><dd><p>mother's weight in pounds at last menstrual period.</p> </dd> <dt><code>race</code></dt><dd><p>mother's race (<code>1</code> = white, <code>2</code> = black, <code>3</code> = other).</p> </dd> <dt><code>smoke</code></dt><dd><p>smoking status during pregnancy.</p> </dd> <dt><code>ptl</code></dt><dd><p>number of previous premature labours.</p> </dd> <dt><code>ht</code></dt><dd><p>history of hypertension.</p> </dd> <dt><code>ui</code></dt><dd><p>presence of uterine irritability.</p> </dd> <dt><code>ftv</code></dt><dd><p>number of physician visits during the first trimester.</p> </dd> <dt><code>bwt</code></dt><dd><p>birth weight in grams.</p> </dd> </dl> <h3>Source</h3> <p>Hosmer, D.W. and Lemeshow, S. (1989) <em>Applied Logistic Regression.</em> New York: Wiley </p> <h3>References</h3> <p>Venables, W. N. and Ripley, B. D. (2002) <em>Modern Applied Statistics with S.</em> Fourth edition. Springer. </p> <h3>Examples</h3> <pre> 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) </pre> <hr /><div style="text-align: center;">[Package <em>MASS</em> version 7.3-51.4 <a href="00Index.html">Index</a>]</div> </body></html>