Table 2.

Grading definition for service collaboration.

Synergy Grade	SE Value	Interpretation
Optimal	$0.8\le SE\le 1$	The service system shows the highest level of synergy, high efficiency is expected.
High	$0.6\le SE<0.8$	There is good collaborative effect and high synergy, the service supply system is expected to run effectively.
Average	$0.4\le SE<0.6$	The system collaborative effect is not significant, its synergy level has potential for further optimization.
Low	$0.2\le SE\le 0.4$	The system collaborative effect is weak, its synergy is low and there is greater field for optimization initiatives.
Lowest	$0\le SE\le 0.2$	The lowest synergy reflects a very weak collaborative effect among the service system, optimization is an evident need.