In situ diffuse scattering of neutrons has been performed at various temperatures on Pd3V, Ni3V, Ni2V, Ni3Cr and Ni2Cr single crystals. The experimental data have been least squares fitted, in order to obtain short range order parameters, from which effective pairwise interactions were deduced up to the fourth neighbour. The least squares procedure is explained, together with the inverse CVM method used to extract interactions from the short range order parameters. We describe the CVM, which approximates the Ising model linking the order parameters to the interactions and the temperature. The trends of the interactions predicted by the electronic structure calculations fit generally with the experimental results. Phase stability and transition temperatures have been deduced from our results : for the DO22 structure, they are in agreement with the experimental situation ; for the Pt2Mo-type structure, the role of the ninth neighbour interaction (330) has been shown to be crucial. We also suspect other interactions, as the triplet in the direction, to be important for this structure