Distribution of difference between position angles of optical polarization plane and jet direction (left column) and fractional polarization (right column) for sources of three different classes according to their VGD vector direction. The optical polarimetric data used in this plot include our polarimetric data joined with the data used by Kovalev et al. (2020). The vertical lines and orange regions indicate the sample mean and standard error. We note the logarithmic scale of the fractional polarization axis.