Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:The mean value of 0.46 obtained for the interclass Hamming distance distribution (see Figure 15b) is practically the same reported in the literature, in spite of the fact that a different iris image database
was used, indicating that the implementation of Daugman’s method used in this work presents coherent results.
Category: