Matched Pair and Block Design I can distinguish between a completely randomized design and a randomized block design. I know when a matched pair experimental design is appropriate and how to implement such a design. Matched Pair and Block Design I can distinguish between a completely randomized design and a randomized block design. I know when a matched pair experimental design is appropriate and how to implement such a design. 4.2 d h.w: p 257: odd

Completely Randomized Design In a completely randomized design, all subjects are randomly assigned to treatment groups. In a completely randomized design, all subjects are randomly assigned to treatment groups.

Block Design In a Block design, subjects are first split into groups called blocks. In a Block design, subjects are first split into groups called blocks. Subjects within each block have some common characteristic. Subjects within each block have some common characteristic. For example: gender, age, education, ethnicity, etc. For example: gender, age, education, ethnicity, etc. Then, within each block, subjects are randomly assigned to treatment groups. Then, within each block, subjects are randomly assigned to treatment groups.

Matched Pairs Design In a Matched pairs design, there are only two treatments. In each block, there is either: Each subject receives both treatments in a random order (more commonly used vs.) or, Each subject receives both treatments in a random order (more commonly used vs.) or, Subjects are matched in pairs as closely as possible and are assigned randomly to each of the treatments. Group 1 does treatment 1 first, group 2 does treatment 1 second. Subjects are matched in pairs as closely as possible and are assigned randomly to each of the treatments. Group 1 does treatment 1 first, group 2 does treatment 1 second.

Outline of a block design: The blocks consist of male and female subjects. The treatments are the three therapies for cancer. The blocks consist of male and female subjects. The treatments are the three therapies for cancer.

Exercise: Charting as an Investment Strategy Some investment advisors believe that charts of past trends in the process of securities can predict future prices. Most economists disagree. In an experiment to examine the effects on using charts, business students trade (hypothetically) a foreign currency at computer screens. Some investment advisors believe that charts of past trends in the process of securities can predict future prices. Most economists disagree. In an experiment to examine the effects on using charts, business students trade (hypothetically) a foreign currency at computer screens.

There are 20 students subjects available, named for convenience A, B, C, …., T. Their goal is to make as much money as possible, and the best performances are rewarded with small prizes. The student traders have the price history of the foreign currency in dollars in their computers. They may or may not also have the software that highlights trends. There are 20 students subjects available, named for convenience A, B, C, …., T. Their goal is to make as much money as possible, and the best performances are rewarded with small prizes. The student traders have the price history of the foreign currency in dollars in their computers. They may or may not also have the software that highlights trends.

In class activity. Describe two designs for this experiment, a completely randomized design and a matched pair design in which each student serves as his or her own control. Describe two designs for this experiment, a completely randomized design and a matched pair design in which each student serves as his or her own control. In both cases, carry out the randomization required by the design. In both cases, carry out the randomization required by the design. Share Share

Possible Designs The randomization will vary with the starting line in Table B. Completely Randomized Design: Randomly assign 10 students to group1 (which has the trend highlighting software) and the other 10 to group 2 (which does not). Randomly assign 10 students to group1 (which has the trend highlighting software) and the other 10 to group 2 (which does not). Compare the performance of group 1 with that of group2. Compare the performance of group 1 with that of group2.

Matched Pairs Design Each student does the activity twice, once with the software and once without. Each student does the activity twice, once with the software and once without. Randomly decide (for each student) whether they have the software the first or the second time. Randomly decide (for each student) whether they have the software the first or the second time. Compare performance with the software and with out it. Compare performance with the software and with out it.

This randomization can be done by a flipping a coin 20 times, or by picking 20 digits from Table B, and using the software first if the digit is even, etc. This randomization can be done by a flipping a coin 20 times, or by picking 20 digits from Table B, and using the software first if the digit is even, etc.

Alternative matched pairs design: Again, all students do the activity twice. Again, all students do the activity twice. Randomly assign 10 students to group 1 and 10 to group 2. Randomly assign 10 students to group 1 and 10 to group 2. Group 1 uses the software the first time; group 2 uses the software the second time. Group 1 uses the software the first time; group 2 uses the software the second time. End End

In Class FR (in notes) 2002B Free Response: score and correct then report to teacher for credit. (in notes) 2002B Free Response: score and correct then report to teacher for credit.