Sixteen quarterly measures of arsenic concentrations (ppb).
EPA.09.Ex.14.4.arsenic.df
A data frame with 16 observations on the following 4 variables.
Sample.Date
a factor indicating the month and year of collection
Month
a factor indicating the month of collection
Year
a factor indicating the year of collection
Arsenic.ppb
a numeric vector of arsenic concentrations (ppb)