Benzene concentrations (ppm) at one background and five compliance wells (four monthly samples for each well).
A data frame with 24 observations on the following 6 variables.
a character vector of the original observations
a numeric vector with
<1 observations coded as
a logical vector indicating which observations are censored
a factor indicating the month of collection
a factor indicating the well number
a factor indicating the well type (background vs. compliance)
USEPA. (1989b). Statistical Analysis of Ground-Water Monitoring Data at RCRA Facilities, Interim Final Guidance. EPA/530-SW-89-026. Office of Solid Waste, U.S. Environmental Protection Agency, Washington, D.C. p.5-18.