Comparison of clump properties of the total UC H II regions and variable UC H II regions. Top panel: spectral index α_{4–8 GHz} UC H II regions vs. the surface densities of their natal clumps for the variable sample (red circles), and the Top7 (blue circles) (6 with reliable α in Table 1), and the total UC H II regions (gray dots) from GLOSTAR (only GLOSTAR here as it has the measured spectral index). Middle panel: bolometric luminosity vs. the clump mass of the natal clumps for the variable UC H II regions, the Top7, and the total UC H II regions of CORNISH and CORNISH. Bottom panel: bolometric temperature vs. the luminosity-to-mass ratio of the natal clumps for the variable UC H II regions, the Top7 variable UC H II regions, and the GLOSTAR and CORNISH UC H II regions. The error bars in each figure correspond to a typical uncertainty of these parameters: 0.2 for α (Yang et al. 2023), 25% for T_bol, 50% for L_bol, M_clump, and L_bol/M_clump (Urquhart et al. 2018, 2022).