Percent difference between the Spearman correlation coefficient including all parameters and the coefficient when the listed parameter is excluded. The larger the difference, the worse the fit without that parameter (i.e. the higher the importance of that parameter). Therefore, the soft X-ray-related parameters are the highest contributors to the predictive capability of the algorithm. “MIR” refers to the WISE colors and the MIR-X-ray flux ratio. “HR” represents the two X-ray HRs. “Soft XR” refers to the two X-ray HRs and the MIR-X-ray flux ratio.