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:In fact, a previous study in the current sample demonstrated that a brief intervention was effective in reducing child behavior problems via improvements in parental positive behavior support (i.e., proactiveness, structuring, and clear communication; Dishion et al. 2008), which included aspects of warmth.
Category: