Study of the Frost Resistance of HDFC Based on a Response Surface Model and GM (1,1) Model

Table 8

Model established index critical value.

Critical value of the index	Accuracy class
	Primary standard	Secondary standard	Three-level standard	Four-level standard
C	0.35	0.50	0.65	0.80
P	0.95	0.80	0.70	0.60
	0.90	0.80	0.70	0.60
	0.01	0.05	0.10	0.20