The results of several statistical tests performed on a large 139 broad absorption line (BAL) QSO with good quality optical spectra and/or optical polarization data are discussed. Correlations between ten optical indices and the polarization degree are symmetrically searched for. The main results can be explained in the framework of a 'two-component' wind model which is a natural extension of the classical wind-from-disk models. In this model, the broad absorption occurs in a dense equatorial wind emerging from the accretion disk, while scattering and polarization mainly take place in a polar region.