A method for predicting statistics of colour differences computed using a ΔE metric given a value of a different ΔE metric is introduced in this paper. The result of this method is the ability to determine what range of values of one metric can be expected for a given ΔE value computed in terms of another metric. This in turn allows for inter–comparison of results from different studies even if these reported their findings in terms of various colour difference formulae. This paper also illustrates the use of the inter–comparison method proposed in it and shows that the method works with very high levels of accuracy and that it can be applied to a range of colour difference metrics including even Euclidean distance in device–dependent colour spaces. The effect of applying advanced colour difference formula in CAM97s2 space is also illustrated and a close relationship with their original CIELAB–based versions is shown.