1. Ch.4.2: Completely Randomized Design DO NOW & Quick Quiz
AP Statistics
Ch.4.2: Completely Randomized Design
DO NOW & Quick Quiz

2. DO NOW: Homework Review
From your Chapter 4 Packet, 4.2 Concept #2:
What are the experimental units, explanatory variable, treatments and response variable?
Experimental units: Each of the 150 students
Explanatory variable: classical music
Treatments: classical music, no music
Response variable: test scores

3. DO NOW: Homework Review
2. What are potential lurking variables in this situation? Study time, tutoring, amount of sleep, etc. How could they affect the results? More studying, tutoring, and more sleep could lead to higher test scores How could we avoid their effects? Randomly assign students to groups so that the effects of lurking variables will be felt equally by all groups in the experiment.

4. DO NOW: Homework Review
3. Describe a completely randomized design for Mr. Tyson’s experiment.
150 statistics students
Random Assignment
Group 1 75 students
Group 2
75 students
Treatment 1 classical music
Treatment 2
No music
Compare Test scores

5. DO NOW: Homework Review
BONUS: How would you carry out the random assignment? Provide enough detail that a classmate could implement your procedure exactly as written. Random number method: Using an alphabetical list of the students, assign each student a number between 01 and 150. Use a calculator to randomly generate 75 unique numbers between 01 and 150. These students belong in the treatment group, where students will listen to classical music while studying. The other students will listen to no music. Hat method: Use 150 equally sized slips of paper. Label 75 of the slips “1” and 75 of the slips “2.” Then mix them up in a hat and have each student draw a number without looking. The students who draw “1” will be assigned to the group that listens to classical music while studying and the students who draw “2” will be assigned to the group that does not listen to music while studying.

6. Quick Quiz Solutions
What are the experimental units, explanatory variable, treatments and response variable?
Experimental units: Each of the 29 students
Explanatory variable: small group discussions
Treatments: small group discussions, view video alone (no small group discussion)
Response variable: performance evaluation

7. Quick Quiz Solutions
2. How can you avoid the effect of potential lurking variables in this experiment? Randomly assign students to treatment groups so that the effects of lurking variables will be felt equally by all groups in the experiment.

8. Quick Quiz Solutions
3. Outline a completely randomized design for this experiment using a flowchart.
29 music students
Random Assignment
Group 1 15 students
Group 2
14 students
Treatment 1 small group
Treatment 2
alone
Compare Evaluations

9. Quick Quiz Solutions
2. Describe how you would carry out the random assignment. Provide enough detail that a classmate could implement your procedure exactly as written. Random number method: Using an alphabetical list of the students, assign each student a number between 01 and 29. Use a calculator to randomly generate 15 unique numbers between 01 and 29. These students belong in the treatment group, where students will meet in small groups. The other students will view the videos alone. Hat method: Use 29 equally sized slips of paper. Label 15 of the slips “1” and 14 of the slips “2.” Then mix them up in a hat and have each student draw a number without looking. The students who draw “1” will be assigned to the group that views the video and discusses it in small groups and the students who draw “2” will be assigned to the group that views the video alone and does not discuss it with a group.