Distribution plot of quantum numbers of rotational transitions measured and fitted for the ground-state doublet of glycinamide. Symbol diameter is proportional to the value of |f_obs-calc|∕σ where f_obs-calc is the residual of fit for a given line and σ is its measurement uncertainty. Red colour identifies outliers with |f_obs-calc|∕σ > 3. The few outliers are all for confidently assigned transitions and may be due either to blends with unassigned lines or incompletely treated perturbation contributions.