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Bulletin of the National Research Centre

Table 4 Estimates, standard errors, and variance inflation factors (VIF) of parameters of the fitted split-plot CCD model

From: Optimization of phenol adsorption from synthetic wastewater by synthesized BiFeO3 perovskite material, using split-plot central composite design

Source

Coefficient estimate

Standard error

VIF

Intercept

87.56

2.82

 

Whole-plot terms:

a-pH

3.97

1.89

1

a2

 − 14.60

1.63

1.04

Subplot terms:

   

B-Tim

4.40

2.26

1

C-Dosage

 − 1.30

2.26

1

aB

0.02

2.99

1

aC

 − 5.95

2.99

1

BC

2.06

2.99

1

B2

 − 11.27

2.01

1.02

C2

 − 10.46

2.01

1.02

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