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Data from
 
  Box, Hunter and Hunter
  "Statistics for Experimenters"
  Wiley 1978
  p. 442-3

"This investigation was concerned with the study of the growth of algal
blooms and the effects of phosphorus, nitrogen, and carbon on algae
growth.  A 2^3 factorial experiment was performed, using laboratory
batch cultures of blue-gree Microcystis aeruginosa.  Carbon (as bi-
carbonate), phosphorus (as phosphate), and nitrogen (as nitrate) were
the variable factors.  The response was algal population, measured
spectrophotometrically."

The responses are measured in some absorbance units.

(Source: R. W. Mann, "Significane of Phosphorus, Nitrogen and
Carbon as Regulators of the Growth of the Alga Microcystis aeruginosa,"
Master's Thesis, Department of Civil Engineering, Tufts University,
Medford, Mass., June 1971.)

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