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:Finally, to conclude the evaluation for the technical performance, the waveforms for both dSE-QuEPI and SEEPI were simulated using measured gradient impulse response functions (26) to assess the influence of inevitable non-ideal performance of the gradient system and determine if correction was needed to achieve an accurate mapping to k-space.
Category: