smokerlead {testtwice}

Pair Differences in Blood Lead Levels in 679 Matched Pairs of One Smoker and One Control.

Description

Data from the 2007-2008 US National Health and Nutrition Examination Survey. There are 679 matched pair differences in blood lead levels in ug per dl, comparing a daily smoker and a nonsmoking control. A daily smoker smoked every day for the last 30 days and smoked at least 10 cigarettes per day. Nonsmokers smoked fewer than 100 cigarettes in their lives. The data are described further in Rosenbaum (2012).

Usage

data("smokerlead")

Format

A data frame with 679 observations on the following 3 variables.

lead

Smoker-minus-control pair differences in blood lead levels, ug per dl.

llead

Smoker-minus-control pair differences in logs of blood lead levels.

dose

Number of cigarettes smoked per day for the smoker in the matched pair.

Details

Pairs were matched for age, gender, education, income and ethnicity.

Source

The data are originally from the 2007-2008 US National Health and Nutrition Examination Survey, but the current example appeared in Rosenbaum (2012).

References

Rosenbaum, P. R. (2012) <doi:10.1093/biomet/ass032> Testing one hypothesis twice in observational studies. Biometrika, 99(4), 763-774.

US National Health and Nutrition Examination Survey.

Examples

data(smokerlead)
attach(smokerlead)
# Compare with Table 1 in Rosenbaum (2012).
quantile(lead,c(0,1/16,1/8,1/4,1/2,3/4,7/8,15/16,1))
quantile(dose,c(0,1/16,1/8,1/4,1/2,3/4,7/8,15/16,1))
oldpar<-par(mfrow=c(1,2))
boxplot(llead,ylab="Difference in Logs of Lead Levels",xlab="Smoker-Control")
abline(h=0,col="red")
plot(dose,llead,ylab="Difference in Logs of Lead Levels",xlab="Cigarettes Per Day")
lines(lowess(dose,llead),col="red")
detach(smokerlead)
par(oldpar)