Quasielastic neutron scattering (QENS) is a widely used technique to provide insights into the dynamics of plastic crystals. Analyzing the data from these experiments requires tting complex functions and selecting between di erent models, since the number of processes is unknown a priori. In this article, we present the case of Succinonitirle. QENS data was successfully analyzed using the Bayesian inference methods under the algorithm FABADA. Besides, a new bayesian approach is presented: Bayesian Free Energy. Although not tested with the problem of Succinonitrile, a theoretical explanation about it is included, together with a model selection example 2018/2019