28. A researcher wants to investigate whether dierent forms of exercise can be used to

help hyperactive children. A group of 90 children is divided into two groups according

to age - those aged 9-12 and those aged 5-9. Within each age group the children are

randomly assigned to one of three groups. The rst group will just do their normal

exercise. The second group will be given an additional exercise routine (moderate).

The third group will be given an additional exercise routine (strenuous). At the end

of a four month period parents will be asked to evaluate their children's progress. Is

this a completely randomized design or a randomized block design? Describe Design

of Experiment.

(a) Completely randomized over one factor (exercise).

(b) Randomized block design, blocking on age, with one factor, exercise.

(c) Randomized block design, blocking on exercise, with one factor, age.

(d) Completely randomized over two factors, exercise and age.

(e) None of the above.