Besides the effective radius R eff , the robust radius R rbt  and the sharpness radius R shp  are introduced. The validity of three kinds of radii, two characteristic radii, for describing the pattern quality are test through numerically generated patterns of a collimated laser beam propagating through a turbulent atmosphere, and main results could be summarized as follows. R rbt  and R eff  are equivalent for Gaussian beams, but the former can be used for more general patterns. Both of them are not valid for evaluating the pattern quality; and R shp  can well used for the purpose. For laser beam patterns in the turbulence under very weak fluctuation condition, in a very limited extent, the pattern quality for half of them will be degraded, and for another half the quality will be refined. With increase of the fluctuation condition, the quality of more and more patterns will be degraded, and there still be some patterns whose quality will be refined in a deeper extent.