Condensed Monte Carlo simulation results have been used for calculating absorption and reduced scattering coefficients from the literature data on the measured total transmittance and total reflectance of samples of the human skin in vitro. The results of several measuring methods have been compared. We have also estimated the range for absorption coefficients and reduced scattering coefficients at 660 and 940 nm from measured intensities at the skin surface as a function of the distance from the location where the light enters the skin by using condensed Monte Carlo simulations for a homogeneous semi-infinite medium. The in vivo values for the absorption coefficients and the reduced scattering coefficients appear to be much smaller than the values from the in vitro measurements, that have been assumed until now. The discrepancies have been discussed in detail. Our in vivo results are in agreement with other in vivo measurements that are available in the literature.