Mass ratio q versus P_orb. Dots are positive measurements from eclipsers and superhumps; triangles are upper limits on q from radialvelocity studies. The curve is the predicted trend if CV evolution is driven by angular-momentum loss at the gravitational-radiation (GR) rate, assuming X = 0.7 and M_1 = 0.8 M_sol. The error in q is likely to be ~15 per cent on the upper branch (say q > 0.10), and somewhat higher on the lower branch. (Figure 6 from Patterson, J. 2011, MNRAS, 411, 2695.)