Counts of mayfly nymphs at low flow in 12 small streams. In each stream, counts were recorded above and below industrial outfalls.
data(Helsel.Hirsch.02.Mayfly.df)
A data frame with 24 observations on the following 3 variables.
Mayfly.Count
Number of mayfly nymphs counted
Stream
a factor indicating the stream number
Location
a factor indicating the location of the count (above vs. below)