Top: spectral variability parameter β versus Eddington ratio λ_E. There is no clear trend for λ_E ≳ −2. Even though the number of points for the first bin is scarce, the absolute value of β for very low Eddington ratio λ_E ≲ −2 is smaller, suggesting that for even lower Eddington ratios it might become positive, transitioning to harder when brighter trend as found by Connolly et al. (2016). Bottom: histogram of Eddington ratio is also shown.