Consider the experiment described in part (a). Describe how you would use a randomized block experiment with blocks based on age. Use three blocks: donors younger than 30 years old, donors 30 to 59 years old, donors 60 and older. (Select all that apply.)
First, assign individuals to the three blocks based on age.
First, use random selection to assign half the individuals to mail solicitation and the other half to phone.
Second, use random selection to assign half the individuals in each block to mail solicitation and the other half to phone.
Second, assign individuals to the three blocks based on age.
Last, compute percentages of donors in each block for each group and compare results within each group.
Last, compute percentages of donors in each group for each block and compare results within each block