How would you use a completely randomized experiment in each of the following settings? Is a placebo being used or not? 1. A charitable non-profit organization wants to test two methods of fundraising. From a list of 1,000 p half will be sent literature about the successful activities of the charity and asked to make another donation. The other 500 donors will be contacted by phone and asked to make another donation. The percentage of people from each group will be compared.
A. Randomly select 100 donors to receive the literature and 900 donors to receive the phone call.
B. A placebo is not being used.
C. A placebo is being used for the remaining 900 donors.
D. After the donation collection period, calculate the average or total amount collected from the 500 donors in the treatment group.
E. After the donation collection period, compare the average or total amount collected from each of the two treatment groups.
F. Randomly select 500 donors to receive the literature and 500 donors to receive the phone call.
2. A tooth-whitening gel is to be tested for effectiveness. A group of 85 adults have volunteered to participate in the study. Of these, 43 are to be given a gel that contains the tooth-whitening chemicals. The remaining 42 are to be given a similar-looking package of gel that does not contain the tooth-whitening chemicals. A standard method will be used to evaluate the whiteness of teeth for all participants. Then the results for the two groups will be compared.
A. A placebo is not being used.
B. After the treatment period, compare the whiteness of the 43 treated adults.
C. Randomly select 43 adults to be given the treatment gel.
D. Randomly select 85 adults to be given the treatment gel.
E. After the treatment period, compare the whiteness of the two groups.
F. The remaining 42 adults receive the placebo gel.
3. How could this experiment be designed to be double-blind?
A. Neither the treatment administrators nor the patients would know which gel the patients are receiving.
B. The patients would not know which gel they or the other patients are receiving.
C. The patients would not know which gel they are receiving.
D. The treatment administrators would not know which gel the patients are receiving.
4. 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 under 30 years old, donors 30 to 59 years old, donors 60 and over.
A. Last, compute percentages of donors in each block for each group and compare results within each group. B. First, assign individuals to the three blocks based on age.
C. Second, assign individuals to the three blocks based on age.
D. First, use random selection to assign half the individuals to mail solicitation and the other half to phone.
E. Second, use random selection to assign half the individuals in each block to mail solicitation and the other half to phone.
F. Last, compute percentages of donors in each group for each block and compare results within each block.