You might consider using a cause-and-effect diagram to get to the root cause of why response time is long. Once you have narrowed the issue to the root cause, you might want to do a literature review to determine best practice. You might also want to contact the patient satisfaction survey vendor to check if the vendor will give you the names of hospitals that have the best scores for satisfaction with response to call bells. What measures would you use to understand if you were improving timely response to call lights?