Measured versus predicted (with the Jones et al. (2018)L_B–M_HI scaling relation) H I masses of HCGs. All measured H I masses are those from the VLA data, except for HCG 30 and 37, which use the GBT measurements. Points circled with black dashed lines are triplets. The solid black line indicates equality and the dashed and dotted lines indicate 1σ and 2σ scatters from the Jones et al. (2018) relation (for a single galaxy). HCG 62 was undetected with the VLA (and has no GBT observation) and is marked as an upper limit.