CONCLUSION: Reducing the number of items in patient satisfaction questionnaires is complex. Patients are willing to specify what is important to them in their ambulatory care, however, most patients volunteer only one or two issues, and these issues vary across patients. When shown a partial list of items from an existing instrument, ceiling effects limit the patients' ability to reveal the relative value of potentially competing items. The disparity in results with the two methods suggests researchers need to be aware of how existing instruments were generated, think about the ability and willingness of patients to discriminate among multiple items with similar themes, and find ways to capture what is important to patients without overburdening them.