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:As the ALSOVA study did not use a validated instrument to rate pain, somatic symptoms (symptoms of discomfort) were evaluated for their association with analgesic use, and assessed with one screening question ‚Äòdiscomfort and symptoms‚Äô from the 15D self-administered, validated, health-related QoL questionnaire [31].
Category: