Refer back to the previous exercise. a. By far the most frequently tested null hypothesis when data is paired is H0: D = 0. Is

Refer back to the previous exercise.

a. By far the most frequently tested null hypothesis when data is paired is H0: µD = 0. Is that a sensible hypothe sis in this context? Explain.

b. Carry out a test of hypotheses to decide whether there is compelling evidence for concluding that on average diagnosis occurs more than 25 months after the onset of symptoms.

Previous Exercise

Cushing's disease is characterized by muscular weakness due to adrenal or pituitary dysfunction. To provide effective treatment, it is important to detect childhood Cushing's disease as early as possible. Age at onset of symptoms and age at diagnosis (months) for 15 children suffering from the disease were given in the article "Treatment of Cushing's Disease in Childhood and Adolescence by Transphenoidal Microadenomectomy" (New Engl. J. of Med., 1984: 889). Here are the values of the differences etween age at onset of symptoms and age at diagnosis:

24 -12 -55 -15-30 -60-14-21 -48-12 -25-53 -6-69 -80