An article in the Journal of Quality Technology (Vol. 13, No. 2, 1981, pp. 111€“114) describes an experiment that investigates the effects of four bleaching chemicals on pulp brightness. These four chemicals were selected at random from a large population of potential bleaching agents. The data are as follows:

(a) Is there a difference in the chemical types? Use a = 0.05.
(b) Estimate the variability due to chemical types.
(c) Estimate the variability due to random error.
(d) Analyze the residuals from this experiment and comment on model adequacy.

Transcribed Image Text:

Chemical 1 Pulp Brightness 77.199 74.466 92.746 76.208 82.876 80.522 79.306 81.914 80.346 73.385 79.417 78.017 91.596 80.802 80.626 78.001 78.358 77.544 77.364 77.386 4