Correlations between final-to-initial ratios of pattern speeds Ω_p and bar lengths L_bar (top) and corotation radii R_CR (bottom). The dashed black line in the bottom panel marks where ℛ would not change; i.e. ℛ_final/ℛ_init = 1. The colour of points in the top panel indicates the mean slowing rate ⟨η⟩. The bars that slow down more lie above the ℛ_final/ℛ_init = 1, which means their ℛ goes up and they also slow down in terms of ℛ.