Parametric optimization of powder mixed electrical discharge machining for nickel-based superalloy inconel-800 using response surface methodology

Table 7 Analysis of variance for MRR (after backward elimination)

Source	Sum of Squares	DF	Mean Square	F - Value	Prob > F
Model	2494.05	7	356.29	190.05	<0.0001	Significant
A	2134.51	1	2134.51	1138.55	<0.0001
B	250.15	1	250.15	133.43	<0.0001
D	5.62	1	5.62	3	0.0915
E	1.05	1	1.05	0.56	0.4591
D²	14.54	1	14.54	7.75	0.0083
E²	22.51	1	22.51	12.01	0.0013
AB	59.27	1	59.27	31.61	<0.0001
Residual	71.24	38	1.87
Lack of Fit	67.73	33	2.05	2.92	0.1165	Not significant
Pure Error	3.51	5	0.7
Cor. Total	2565.29	45
Std. Dev. = 1.37					R-Squared = 0.9722
Mean = 16.24					Adj R-Squared = 0.9671
C.V. = 8.43					Pred R-Squared = 0.9599
PRESS = 102.79					Adeq Precision = 57.25