K_s-band polarization fraction curves, see Appendix C.1 and Table C.1 for the analytical expressions using scaled beta distribution. Best-fit curves with gray segments inaccessible from observation, based on system inclination assuming infinitely thin disks. The error bar on the top right, which could be used to infer the systematic uncertainty from the fitting method, is from the standard deviation of three sets of MWC 758 best-fit results.