De-inking of newsprint
A data frame with 27 observations on the following 3 variables.
amount of alkali in the solution
hardness of the water - an ordered factor
a measure of brightness
One step of recycling newsprint is to "de-ink" the newsprint, that is to remove the ink. The brightness of the paper pulp after a de-inking process is a measure of how well the process to remove the ink worked.
Peter R. Nelson, Marie Coffin and Karen A. F. Copeland (2003), Introductory Statistics for Engineering Experimentation, Elsevier. (Appendix A)
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