Filling factor f_filling versus eccentricity for a subsample of ellipsoidal variables. The data points are color coded based on the orbital period. For the most eccentric binaries, the filling factor at apo- and periastron is included as unfilled circles, connected to the average value obtained considered a zero eccentricity. The top and right panel shows the distribution (gray histogram) of filling factors and eccentricities, respectively. The top panel includes the distribution of filling factors for all the ellipsoidals having reliable measurements for their radii (black-edge histogram).