Experimental Study on Lateral Resolution of Phased Array Ultrasonic Testing of Irregular Structure Weld Defects

Table 10

Variance analysis TABLE of regression model.

Source	Regression model
	Df	Sum of squares	Mean square	F value	P value
Model	9	128.78	14.31	18.71	<0.0001
X1	1	22.17	22.17	28.99	0.0003
X2	1	21.35	21.35	27.93	0.0004
X3	1	40.84	40.84	53.42	<0.0001
X1X2	1	1.28	1.28	1.67	0.2248
X1X3	1	0.98	0.98	1.28	0.2840
X2X3	1	25.21	25.21	32.96	0.0002
X1^2	1	4.79	4.79	6.26	0.0313
X2^2	1	9.37	9.37	12.25	0.0057
X3^2	1	6.03	6.03	7.89	0.0185
Residual	10	7.65	0.76
Lack of fit	5	6.27	1.25	4.54	0.0612 not significant
Pure error	5	1.38	0.28
Cor total	136.43	19
R^2 = 0.9440				Adeq precision = 16.750