Analysis and Prediction of the Coupling Coordination Relationship between Tourism and Air Environment: Yangtze River Economic Zone in China as Example

Table 4

Accuracy grade of the gray model.

Accuracy	r	C
Unqualified	<0.60	>0.80	<0.60
Grade 4	≥0.60	≤0.80	≥0.60
Grade 3	≥0.70	≤0.65	≥0.70
Grade 2	≥0.80	≤0.50	≥0.80
Grade 1	≥0.90	≤0.35	≥0.95