A psychiatrist wonders if people with panic disorder benefit from one particular type of treatment over any

Question:

A psychiatrist wonders if people with panic disorder benefit from one particular type of treatment over any others. She randomly selects patients who have used one of the following treatments: cognitive therapy, behavioral therapy, or medication. She asks them to rate on a scale from 1 to 10 how much the treatment has led to a decrease in symptoms (with a score of 10 being the greatest reduction in symptoms). Test the null hypothesis that the different treatments for panic disorder did not differ in how much they helped these patients.