A non-informative prior P (θ) = 1 is often used in adjustment procedures where all **data** are used simultaneously. Inclusion of prior information is an important aspect of the procedures commonly used in nuclear **data** evaluation, where datasets are added to a previous adjustment procedure. In such a case the posterior of the previous dataset evaluation can be used as a prior. Then, only the new dataset, in combination with this prior, is employed in forming the new posterior function that defines the revised evaluation..