The marketing firm in problem 1 has decided that age may also have an affect on attention span. They decide to assign the children to groups of fifteen 9 to 10 year olds, fifteen 7 to 8 year olds, and fifteen 5 to 6 year olds. Within each group, the children are asked to watch one 60-second commercial for one of the three types of toys and their attention spans are measured in seconds.

a. Is this an experiment or an observational study?
b. If it is an experiment, is it randomized or block design?
c. If it is an experiment, identify the explanatory and response variables.
d. If this is an experiment, draw a diagram representing the levels and treatments.