6- How would you use a completely randomized experiment in each of the following settings? Is a placebo being used or not? Be specific and give details.

(a) A charitable nonprofit organization wants to test two methods of fundraising. From a list of 1,000 past donors, 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. (Select all that apply.)

After the donation collection period, compare the average or total amount collected from each of the two treatment groups.

A placebo is not being used.

Randomly select 100 donors to receive the literature and 900 donors to receive the phone call.

After the donation collection period, calculate the average or total amount collected from the 500 donors in the treatment group.

Randomly select 500 donors to receive the literature and 500 donors to receive the phone call.

A placebo is being used for the remaining 900 donors.

(b) 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. (Select all that apply.)

Randomly select 85 adults to be given the treatment gel.

After the treatment period, compare the whiteness of the 43 treated adults.

A placebo is not being used.

The remaining 42 adults receive the placebo gel.

After the treatment period, compare the whiteness of the two groups.

Randomly select 43 adults to be given the treatment gel.

(c) How could this experiment be designed to be double-blind?

Neither the treatment administrators nor the patients would know which gel the patients are receiving.

The patients would not know which gel they or the other patients are receiving.

The treatment administrators would not know which gel the patients are receiving.

The patients would not know which gel they are receiving.

(d) 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. (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.

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.

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.

7- Make a statistical profile of your own statistics class. Items of interest might be any of the following.

(a) Height, age, gender, pulse, number of siblings, marital status

(b) Number of college credit hours completed (as of beginning of term); grade point average

(c) Major; number of credit hours enrolled in this term

(d) Number of scheduled hours working per week

(e) Distance from residence to first class; time it takes to travel from residence to first class

(f) Year, make, and color of car usually driven

What directions would you give to people creating these questions? For instance, how accurate should the measurements be? Should age be recorded as of last birthday? (Select all that apply.)

Allow some questions to be open for interpretation.

No questions should be misleading.

Use vague wording such as "often," "seldom," and "occasionally."

Commonsense rules should be stated for any numerical answers.

Use leading and biased questions.

Since some items might be sensitive information, design a data form that can be filled out anonymously.

Questions should be worded in a clear, concise, and unbiased manner.