Lead concentrations (mg/Kg) in soil samples at a reference area and a
cleanup area. Nondetects reported as
<39. There are 14 observations
for each area.
A data frame with 28 observations on the following 4 variables.
a character vector of original lead concentrations (mg/Kg)
a numeric vector of lead concentrations with
<39 coded as
a logical vector indicating which observations are censored
a factor indicating the area (cleanup vs. reference)
USEPA. (1994b). Statistical Methods for Evaluating the Attainment of Cleanup Standards, Volume 3: Reference-Based Standards for Soils and Solid Media. EPA/230-R-94-004. Office of Policy, Planning, and Evaluation, U.S. Environmental Protection Agency, Washington, D.C. pp.6.20–6.21.