Comparison between the gas-to-dust ratio and different parameters (from left to right : ratio of CO J=2-1 velocity-integrated line flux to the IRAS 60 μm flux, Ṁ_gas, P, and $R_{\mathrm{F}\mathrm{U}\mathrm{V}/\mathrm{N}\mathrm{U}\mathrm{V}}^{\mathrm{c}\mathrm{o}\mathrm{r}\mathrm{r}}$). The colour and shape of the markers represent the stellar variability and chemistry type as in Fig. 4. The dashed lines represent linear fits to the points, and the dotted line in the first panel is the best fit excluding R UMa. Error bars of $R_{\mathrm{F}\mathrm{U}\mathrm{V}/\mathrm{N}\mathrm{U}\mathrm{V}}^{\mathrm{c}\mathrm{o}\mathrm{r}\mathrm{r}}$ are estimated as in Fig. 5. Empty arrows are upper limits for non-detections in the FUV.