Copper concentrations (ppb) at three background and two compliance wells (eight monthly measures at the background wells, four monthly measures at the compliance wells).
EPA.09.Ex.17.4.copper.dfA data frame with 40 observations on the following 6 variables.
Montha factor indicating the month of collection
Wella factor indicating the well number
Well.typea factor indicating the well type (background vs. compliance)
Copper.ppb.origa character vector of original copper concentrations (ppb)
Copper.ppba numeric vector of copper concentrations with nondetects set to their detection limit
Censoreda logical vector indicating which observations are censored