title: Analysing the relationship between maternal weight gain and birthweight: exploration of four statistical issues.
abstract: Four statistical issues concerning the analysis of birthweight and maternal weight gain during pregnancy are discussed: (1) Part-whole correlation is described (e.g. the correlation between total maternal weight gain and her infant's birthweight). (2) The choice between a ratio or two separate explanatory variables is explored (e.g. body mass index or using maternal weight and height separately). (3) Two statistical properties (bias and power) when a binary variable replaces a continuous variable are discussed (e.g. consequences of using low birthweight instead of reported birthweight). (4) A model selection procedure is presented to provide a way to select a useful subset of variables from a large number of available explanatory variables to model an outcome variable (e.g. birthweight). These issues are illustrated with a set of 4017 births from Moffitt Hospital at the University of California, San Francisco. Furthermore, these four issues arise in a number of applications of statistical methods to data collected to study the epidemiology of newborn infants.
authors.affiliation: Division of Biostatistics and Information Science, School of Public Health, University of California, Berkeley 94720-7360, USA.
authors.forename: S
authors.initials: S
authors.lastname: Selvin
authors.forename: B
authors.initials: B
authors.lastname: Abrams
mesh_terms: D015982:Bias; D001724:Birth Weight; D015992:Body Mass Index; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D015233:Models, Statistical; D015999:Multivariate Analysis; D016017:Odds Ratio; D011247:Pregnancy / Q000502:physiology*; D012044:Regression Analysis; D012107:Research Design; D015430:Weight Gain / Q000502:physiology*