AP Statistics
ASSIGNMENT #14
Intro to Experimental Design
Statisticians wonder if smart phones with access to social media sites/apps., like Twitter impact
student completion percentages of classwork assignments. Volunteer students in the same classes
will be divided into three groups of required tweeting (o tweets, 20 tweets and 50 tweets) during
the school day and at the end of the day the amount of classwork completion will be measured.
Describe what this experiment would look like for a group of 30 student volunteers who all have the same classes.
#bestapstatsquestionever
Research Question
Subjects/Experimental Units
Explanatory Variable(s)/Factor(s)
Quantitative/Categorical?
Treatment(s)
(Factor levels)
Response Variable(s)
Quantitative/Categorical?
Describe the experimental
design in words and/or
diagrams.
Explain how the experimental
design principles apply in this
study.

Control

Random Assignment

Replication
HOMEWORK: Continue to Read Chapter 13, and start chapter 13 online assignment.
AP Statistics
ASSIGNMENT #14
Intro to Experimental Design
Any blocking used? If so,
describe the blocking and why it
was used.
Any blinding used? If so,
describe the blinding in context.
What concerns do you have
about the design of this study?
What statistical analysis
techniques are appropriate for
this study?
What conclusions can be drawn
from the study?
Summary: If you were to tutor for another AP student, what would you tell them to be careful when they are working
on an Experimental Design question
HOMEWORK: Continue to Read Chapter 13, and start chapter 13 online assignment.
AP Statistics
Research Question
Subjects/Experimental Units
Explanatory Variable(s)/Factor(s)
Quantitative/Categorical?
Treatment(s)
(Factor levels)
Response Variable(s)
Quantitative/Categorical?
ASSIGNMENT #14
Intro to Experimental Design
Do smart phones with access to social media sites/apps. like Twitter impact student completion
percentages of classwork assignments?
30 student volunteers who take the same classes
Tweeting amounts (quantitative)
3 Levels – 0 tweets, 20 tweets and 50 tweets
3 Treatments – treatment 1- the group who makes 0 tweets
– treatment 2- the group who makes 20 tweets
– treatment 3- the group who makes 50 tweets
Percentage of classwork completed in a day (quantitative)
Describe the experimental design in
words and/or diagrams.
Explain how the experimental
design principles apply in this study.
Any blocking used? If so, describe
the blocking and why it was used.
Any blinding used? If so, describe
the blinding in context.
What concerns do you have about
the design of this study?
What statistical analysis techniques
are appropriate for this study?
What conclusions can be drawn
from the study?

Control – we are controlling outside factors by having students all in the same classes so
presumably they have equal amounts of work to do.

Random Assignment – assign each student a number 1-30. Put the numbers 1-30 on
individual sheets of paper of equal size. Put the papers in a hat. Shake the hat. Pull out
10 slips of paper. The students corresponding to those numbers go into treatment 1 (0
tweets). Repeat the pulling out papers process 2 more times. The second group of
students corresponding to the second group of 10 pieces of paper get treatment 2 (20
tweets) and the same with group 3 going into treatment 3 (50 tweets).

Replication – each treatment gets 10 people in it so there is replication of each
treatment 10 times.
No blocking used
Single blinding – the subjects obviously must know how many tweets they sent but the person
measuring classwork percentage completion doesn’t need to know what group the students are
in.
We should probably do matched pairs on the same kids. Maybe there are certain kids who just
don’t do a lot of work and randomly they could all end up in the same group. This might
interfere with the effect of tweeting on classwork completion. We may mistake tweeting as an
influence when it really might be student diligence.
We would need to compare the percentages between the 3 groups to see if they are statistically
different from one another.
Whether or not tweeting in differing amounts affects classwork completion percentages for
these 30 volunteers only!!! No generalization these are volunteers not a sample from a
population!!!
HOMEWORK: Continue to Read Chapter 13, and start chapter 13 online assignment.
AP Statistics
ASSIGNMENT #14
Intro to Experimental Design
HOMEWORK: Continue to Read Chapter 13, and start chapter 13 online assignment.