1. Crest Prevents Cavities
Team24

2. Subjects
• 500 Volunteers
• Ages 18-25
• Natural teeth (no dentures)

3. Treatment
• Crest Toothpaste
• Leading brand of toothpaste

4. Response Variable
• How many cavities they receive after 3
months

5. DIAGRAM
RANDOM ASSIGNMENT
Volunteers
(as specified
in previous
slide)
Brush With Crest
Toothpaste
Compare the amount of
cavities received
Brush with leading
toothpaste brand

6. Control
• Every participant has the same eating,
drinking, and brushing cycle
• All participants eat the same food and
drink the same thing
• Brush twice a day, once after breakfast
and once after dinner (must be the
same time for everyone)

7. Randomization
• All participants lined up alphabetically
• Given numbers (first person is 1, second person
is 2, etc.)
• Use RandInt on calculator, ignoring repeats,
get 250 numbers
• Those people are in the Crest group, the other
250 in the leading brand group.

8. Replication
• Repeat 3 times, ten combine the results
for a bigger sample size

9. O
N
O
L
B
K
C
G
IN

10. Blinding
• Both the participants and the dentist are
not able to know which group they are
part of
• A third party keeps track of who is in
which group

11. Concerns
• How to monitor that everyone is eating,
drinking and brushing on the same
schedule to prevent bias