Correlation plot of the radius and velocity dispersion of all groups. The black line indicates the relation by Larson (1981), the green, red, and blue lines show the formula by Ballesteros-Paredes et al. (2011) for an H₂ column density of 10²¹ cm^-2, 10²² cm^-2, and 5 × 10²² cm^-2. The purple line shows a power-law fit to the data with an exponent of 0.4 ± 0.02. The contour plot is shown in the upper panel with the range of the logarithm of the radius and the velocity dispersion divided into bins of 0.3.