A data set from Oehlert (2000) \emph{A First Course in Design and
Analysis of Experiments}, New York: W. H. Freeman.

Data originally from McElhoe, H. B. and W. D. Conner (1986). ``Remote
measurement of sulfur dioxide emissions using an ultraviolet light
sensitive video system.'' {\em Journal of the Air Pollution Control
Association\/}~{\em 36}, 42--47.

Columns are source of smoke and ratio of Visiplume to standard reading.
Sources 1-4 are bag, smoke, coal plant 1, coal plant 2.