40. In a study of processes used to remove impurities from cellulose goods (“Optimization of Rope-Range Bleaching of Cellulosic Fabrics,” Textile Research J., 1976: 493–496), the following data resulted from a 24 experiment involving the desizing process. The four factors were enzyme concentration (A), pH (B), temperature (C), and time (D).

Starch %

by Weight EnTreat- zyme Temp. Time 1st 2nd ment (g/L) pH (°C) (hr) Repl. Repl.

(1) .50 6.0 60.0 6 9.72 13.50 a .75 6.0 60.0 6 9.80 14.04 b .50 7.0 60.0 6 10.13 11.27 ab .75 7.0 60.0 6 11.80 11.30 c .50 6.0 70.0 6 12.70 11.37 ac .75 6.0 70.0 6 11.96 12.05 bc .50 7.0 70.0 6 11.38 9.92 abc .75 7.0 70.0 6 11.80 11.10 d .50 6.0 60.0 8 13.15 13.00 ad .75 6.0 60.0 8 10.60 12.37 bd .50 7.0 60.0 8 10.37 12.00 abd .75 7.0 60.0 8 11.30 11.64 cd .50 6.0 70.0 8 13.05 14.55 acd .75 6.0 70.0 8 11.15 15.00 bcd .50 7.0 70.0 8 12.70 14.10 abcd .75 7.0 70.0 8 13.20 16.12

a. Use Yates’s algorithm to obtain sums of squares and the ANOVA table.

b. Do there appear to be any second-, third-, or fourth-order interaction effects present? Explain your reasoning.

Which main effects appear to be significant?