Table 3.

Correlation coefficients among different approaches.

	DEA	DEA-BC	L-DEA-BC	U-DEA-BC	L-FDEA (α = 1)	U-FDEA (α = 1)
DEA
DEA-BC	0.963 **
L-DEA-BC	0.888 **	0.973 **
U-DEA-BC	0.987 **	0.963 **	0.888 **
L-FDEA (α = 1)	0.693 **	0.626 **	0.547 **	0.692 **
U-FDEA (α = 1)	0.770 **	0.778 **	0.747 **	0.769 **	0.861 **
$I_0$	0.721 **	0.650 **	0.571 **	0.720 **	0.992 **	0.862 **

** Correlation is significant at p < 0.001. DEA: Data Envelopment Analysis; DEA-BC: Data Envelopment Analysis bias corrected; L-DEA-BC: lower end of the confidence interval of bias-corrected DEA scores; U-DEA-BC: upper end of the confidence interval of bias-corrected DEA scores; L-FDEA: lower end of the interval of fuzzy DEA scores; U-FDEA: upper end of the interval of fuzzy DEA scores.