Comparison of 150 daily smokers and 5 matched control nonsmokers from NHANES in terms of blood lead levels in mu-g/L. The matching controlled for gender, age, race education level, and household income. The data were used in Rosenbaum (2013) to contrast design sensitivity with matched pairs and with multiple controls. See also lead250. Used as an example to illustrate the senmv function in the sensitivitymv package.