Independent Actual (Coded) levels
Variables (ml) Negative (-0.5) Zero (0) Positive (+0.5) Finer to Finest Coded
Methanol (right sided 6.0 6.5 7.0 A
Chloroform (left-sided) 4.0 3.5 3.0 B
Ratio A: B (Two-sided) 1.0 1.5 2.0 C
Dependant Constraints
Y1 = Absorbance 0.277≤Y1≥0.318
Central Composite; independent Design
Runs-Code Variables
Independent Response (Y)
A B C Observed Predicted
  0 0 +0.5 0.318 0.288
  +0.5 +0.5 +0.5 0.298 0.312
  +0.5 -0.5 -0.5 0.312 0.277
  +0.5 -0.5 +0.5 0.297 0.298
  +0.5 +0.5 +0.5 0.296 0.291
  0 0 -0.5 0.316 0.296
  0 0 0 0.295 0.295
  0 0 0 0.291 0.297
  -0.5 +0.5 -0.5 0.277 0.296
  +0.5 0 0 0.285 0.285
  0 +0.5 0 0.287 0.290
  -0.5 -0.5 +0.5 0.291 0.286
  0 0 0 0.297 0.316
  -0.5 +0.5 +0.5 0.296 0.318
  -0.5 -0.5 -0.5 0.289 0.295
  0 0 0 0.298 0.295
  0 0 0 0.291 0.294
  0 0 0 0.295 0.294
  0 0 0 0.296 0.295
  0 -0.5 0 0.296 0.295
Finer to Finest” designed model equation
Term Model A B C AB AC BC A2 B2 C2 Lack of Fit
Fvalue 217.1 350.0 85.9 3.94 8.76 197.7 123.2 554.5 92.4 1141.2 0.90
Significant   to   Non-significant
pvalue; Prob.>F <0.0001 0.075 0.014 < 0.0001 0.5204
R2 R-Square Adjusted Predicted SD Mean % CV
Values 0.9949 0.9903 0.9573 0.0095 0.30 0.32
"Prob > F" values less than 0.0500 indicate model terms are significant and greater than 0.1000 indicate the model terms are not significant.
Table 2: Results of central composite designed (CCD) “finer to finest” spaces.