Ratio of the average beta energy (from BetaShape) to the NUBASE2020 Q-value. The top panel shows results for β⁺ emissions, and the bottom panel for β⁻ emissions. Data are shown for distinct isomeric states (I = 1 corresponds to first isomeric states, in darker tones, and I = 0 to ground states, in lighter tones), alongside the global average and a linear fit over atomic number Z.