This data set contains yearly observations by the Environmental Protection Agency
on the concentration of sulfur dioxide in parts per billion, based on 32 sites.
I use this for in-class illustration. Note that the national standard is
75 parts per billion. Data are the national trend.
A data frame with the following 4 variables.
yearthe year
valuethe mean concentration of sulfur dioxide in the air
based on 32 trend sites, in parts per billion
ubthe lower bound of the value (10th percentile)
lbthe upper bound of the value (90th percentile)
Source
Environmental Protection Agency ("Sulfur Dioxide Trends")