1. WARM – UP
Burger King has developed a new and improved chicken sandwich. They want to determine whether the cooking method (broiled vs. fried) and/or the cheese selection (American, Swiss or mozzarella) will affect sales. 60 Burger King restaurants are selected from the country.
What are the experimental Units?
What are the explanatory variables or factors?
What is the Response variable?
How many levels are there?
How many treatments are there?
How many experimental units are required for each treatment?
Use a Diagram to describe a Completely Randomized Experiment.
The BK Restaurants
Cooking Method
Cheese selection
Sales
2 and 3 6 10

2. 7. Use a Diagram to describe a Completely Randomized Experiment.60
BK’s
10 – Broil/American
Compare
Sales
Random Assignment HOW?
10 – Broil/Swiss
10 – Broil/Mozz
10 – Fried/American
10 – Fried/Swiss
10 – Fried/Mozz 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

3. Example 2
They should perform a random survey.

6. Principles of Comparative Experimental Design (continued)
BLOCKING: If we group similar individuals together (Homogeneous grouping) and then randomize within each of these blocks, we can reduce variation due to the difference among the blocks.
Unlike the first three principles, is not required in an experimental design.
The BEST experiments use Randomization, Controls, Replication, and Double-Blinding.

7. Example 1
A research doctor has discovered a new ointment that she believes will be more effective than the current medication in the treatment of shingles (a painful skin rash). Eight patients have volunteered to participate in the initial trials of this ointment. You are the statistician hired as a consultant to help design a completely randomized experiment.
Suppose the last names of the patients start with the letters A to H. Using the random numbers listed below, show which patients you will assign to each treatment. Explain you randomization procedure clearly.
Can this experiment be double-blind? How?
Its is suspected that males react differently to the ointment than females. Redesign your experiment with this extra info in mind.

8. Suppose the last names of the patients start with the letters A to H
Suppose the last names of the patients start with the letters A to H. Using the random numbers listed below, show which patients you will assign to each treatment. Explain you randomization procedure clearly

9. Can this experiment be double-blind? How?
Assuming that the ointments looked alike, it would be possible to blind the experiment for the patient and the evaluating doctor. If both the subject and the evaluator are blinded, the experiment is double-blind.
Its is suspected that males react differently to the ointment than females. Redesign your experiment with this extra info in mind.
Before randomly assigning patients to treatments, identify them as male or female. Having blocks for males and females will eliminate variation due to gender improving the experiment.

10. HW: PAGE 316: 34-36, 41, 42 Double-blind experiment
This double-blind experiment has 1 factor (vitamin E), at 2 levels (vitamin E and no vitamin E), resulting in 2 treatments. The response variable measured is the time it takes the patient to recover from the surgery. Randomly select half of the
patients who agree to the study to get large doses of vitamin E after surgery. Give the other patients in the study a similar looking placebo pill.

11. This experiment has 1 factor (reading program), at 2 levels (phonics and whole language), resulting in 2 treatments. The response variable is reading score on
an appropriate reading test after a year in the program. After randomly assigning students to teachers, randomly assign half the reading teachers in the district to use each method. There may be variation in reading score based on school within the district, as well as by grade. Blocking by both school and grade will reduce this variation.

12. Example
A research doctor has discovered a new ointment that she believes will be more effective than the current medication in the treatment of shingles (a painful skin rash). Eight patients have volunteered to participate in the initial trials of this ointment. You are the statistician hired as a consultant to help design a completely randomized experiment.
Describe how you will conduct this experiment.

13. Describe how you will conduct this experiment..

14. This experiment has 1 factor (type of gasoline), at 2 levels (premium
and regular), resulting in two treatments. The response variable is the difference in gas mileage. A matched pairs experiment where you run all cars with both types, draining the tanks, should be used. Randomly assign which type of gas is used first.

15. This experiment has 1 factor (hand), at 2 levels (right, left), resulting in
2 treatments. The response variable is the difference in deactivation time between left and right hand. Find a group of volunteers. Using a matched design, we will require each volunteer to deactivate the machine with his or her left hand, as well as with his or her right hand. Randomly assign the left or right hand to be used first.

16. This experiment has two factors (water temperature, wash cycle). The
factor water temperature has 2 levels (cold, hot), and the factor wash cycle has 2 levels (regular, delicates). 2 factors, at 2 levels each, results in 4 treatments (hot-regular, hot-delicates, cold-regular, cold-delicates). The response variable is the level of cleaning of the grass stains. It would be nice to have 32 shirts with which to experiment, so that we could randomly assign 8 shirts to each treatment group, but equal numbers of shirts in each group are not necessary.