Gummy Bear Catapults Activity
Two-way ANOVA
Lab 9
Data collected in class on Monday March 21, 2011.
Turn this in for your lab on Friday March 25, 2011.
The SPSS work on the last page can be done in lab.
Supplies: (per 4-person group) 2 wide popsicle sticks, 2 skinny popsicle sticks, 2 pencils,
4 rubber bands (skinny or fat?), gummy bears (1 or 2), gummy worm (?), ruler.
In this activity, each group will create two catapults: one using skinny popsicle sticks,
and one using wide popsicle sticks.
Some possible ways to do two-way ANOVA:
Factor 1: wide vs. skinny popsicle sticks
Factor 2: gummy bears vs. gummy worms
Factor 2: positions on length of stick for launching
Factor 2: vertical vs. horizontal gummy bear positioning
In each 4-person group, these are the tasks:
Job 1: Loader/Launcher
Job 2: Holder (keeps the launch equipment steady)
Job 3: Measurer
Job 4: Data recorder and supervisor
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Your name:
Class time:
T.A.:
MW Lecturer:
Partner #1:
Partner #2:
Partner #3:
Gummy Bear Catapult Activity for Two-way ANOVA
1. (1 point) Complete the table below to list the factors and the treatments.
Factor 2
Factor 1
Stick width
Skinny stick
Wide stick
Trt #1:
Skinny &
Trt #2:
Skinny &
Trt #3:
Wide &
Trt #4:
Wide &
2. (1 point) What is your response variable and unit of measurement?
3. (1 point) Record your data below and then enter it into SPSS.
Run #
Trt #1:
Skinny &
Trt #2:
Skinny &
Trt #3:
Wide &
Trt #4:
Wide &
1
2
3
4
5
6
7
8
9
10
4. (1 point) Using your calculator, find the mean for each treatment group.
Treatment
Mean
1
2
3
2
4
5. (2 points) By hand (before you use SPSS), create a means plot using the means that
you found in Question #3. Use wide vs. skinny popsicle sticks for your x-axis, and
use your Factor 2 for the different lines.
6. (1 point) Why do we care whether it is appropriate to pool the variances?
7. (3 points) State the 3 sets of hypotheses for the two-way ANOVA test.
End of what you need to finish in lecture class.
The rest needs to be done with SPSS in lab.
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Type your data into SPSS.
8. (4 points) Create a means plot using SPSS. Describe what the plot tells you about
the two main effects and the interaction.
9. (1 point) Use SPSS to report the means and standard deviations for all 4 treatments.
Treatment
Mean
Standard deviation
10. (2 points) Is it appropriate to pool the variances? How do you know?
11. (3 points) Regardless of your answer to #10, use SPSS to run two-way ANOVA on
your data. Report your conclusions in terms of the story. Be sure to state whether
your results refer to the sample or the population.
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SPSS Instructions for Lab 9
Students need to print the following SPSS output to submit with the lab: table of
summary statistics, means plot, two-way ANOVA test.
Two-way ANOVA
Analyze  General Linear Model  Univariate
Move “Distance” into the “Dependent Variable” box and
Move both “stick” and whatever your other factor is into the “Fixed
Factor(s)” box
 Click on “Plots.” Move “stick” to the horizontal axis box and whatever
your other factor is to the separate lines box. Click the “Add” button to
move that combination to the bottom box. Click “Continue.”
 Click on “Options.” Move “stick” and the other factor into “Display Means
for” box and check “Descriptive statistics” box. Click “Continue.”
 OK
If you want to switch the stick width on the x-axis, you can double click on
the means plot to go to “chart editor.” Then double-click on one of the
widths in the x-axis. Click on the “categories” tab in the “properties”
window. Click on one width at a time, and then the up or down arrows to
move it up or down the list. When finished, click “apply” and then “close.”
“X” out of the “chart editor” window to get back to the regular output file.
Then you can copy and paste the means plot into a Word document.
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