Electrical and optical characterization was performed to obtain information about the doping and compensation levels of samples cut from boron doped, physical vapor transport (PVT) grown 6H-SiC crystals. Values for N-A and N-D can be derived from analysis on temperature dependent Hall effect measurement data. The charge carrier concentration p at room temperature depends approximately linearly on N-A/N-D. The below band-gap absorption (BBGA) maximum at about 730 nm is correlated mainly to N-A, and, for constant N-A, is slightly anti-correlated to N-D. The same results can be obtained from an rootalpha vs. E plot extrapolated to alpha = 0 in the near band-gap region, as the broad absorption band induces a shift in the optically detected band-gap towards lower energies. Absorption measurements can give an estimation of N-A-N-D in boron doped SiC samples, and from wafers cut from the same crystal, the concentration of boron and compensating impurities can be evaluated.