Abstract The standard method for determining the relative transition probabilities of vibrational-rotational bands from experimental data is examined. It is shown that the relative intensities in the high overtone sequences are likely to be similar to those for a linear dipole moment, and that it is impossible to predict either the dipole moment or the intensities in sequences with lower Δv values from them. When this is taken into account the method is found to be satisfactory in its application to synthetic data derived from a model moment. Procedures for determining the signs of ratios of transition integrals based on experimental data are noted. The method is applied to OH using the experimental data of Krassovsky et al. and Garvin et al. on the sequences Δv = 2 to Δv = 7, though the lack of measurements on the Δv = 1 sequence gives rise to ambiguity in the dipole moment and in the transition probabilities for this sequence. Further experimental work is needed. An attempt is made to calculate the rates of population of the various vibrational levels and the effect on these of the ambiguity is demonstrated.