Interactive Statistics

3.20 An experiment was conducted to compare two different methods of teaching piano in indi- vidual lessons to beginning pupils of five different ages (6, 7, 8, 9, and 10 years). Four piano teachers took part in the experiment. Each teacher taught six pupils at each of the five age levels. For each group of six pupils at each age level, the first three randomly selected pupils were assigned to Method I and the remaining three were taught with Method II. An inde- pendent examiner rated each pupil's progress after one year of lessons. The examiner did not know which method had been used with each pupil. (a) Identify the response variable(s). (b) Identify the explanatory variable(s)