Table 10: Coefficients in terms of coded factors for copper.

FactorCoefficient estimateDOFStandard error95% CI low95% CI highVIF

Intercept48.0010.962945.7850.22
A-CD24.0010.833922.0825.921.0000
B-solvent8.2510.83396.3310.171.0000
C-time15.5010.833913.5817.421.0000
AB0.500011.18−2.223.221.0000
AC7.5011.184.7810.221.0000
BC2.5011.18−0.21935.221.0000
A2−6.5011.13−9.10−3.901.02
B28.0011.135.4010.601.02
C21.5011.13−1.104.101.02