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:Since analysis and interpretation of interactions are more straightforward with dichotomous factors [50], SES was split into two classes of risk, namely ‘low’ (SES 10–30) and ‘middle/high’ (SES 40–90), based on theoretically meaningful cutoff points as available from existent literature [51, 52].
Category: