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Session 7:
Homework
Is there an association between the length of your forearm (elbow to wrist) and the length of your feet?
The following are measurements, in millimeters, for forearm length and right-foot length for 20 people:
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N = 20 measurements
Mean forearm length = 262.1
Mean foot length = 255.7 |
Scatter Plot

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Problem H1 | |
Describe the association between forearm length and foot length.
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Problem H2 | |
Use the mean forearm length and the mean foot length to determine the quadrants and number of points in each quadrant.
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Problem H3 | |
a. | Use the quadrants from Problem H2 to create the contingency table for this data. |
b. | What percentage of people with above-average forearm lengths also have above-average foot lengths? |
c. | What percentage of people with above-average forearm lengths also have below-average foot lengths? |
d. | What percentage of people with below-average forearm lengths also have below-average foot lengths? |
e. | What percentage of people with below-average forearm lengths also have above-average foot lengths? |
f. | What do these percentages say about the strength of the association between forearm length and foot length? |
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Problem H4 | |
Consider the line Foot Length = Forearm Length (YL = X).
a. | Complete the table below. |
b. | Determine the SSE for this data. |
When you click "Show Answers," the filled-in table will appear below the problem. Scroll down the page to see it.
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b. The SSE, (256 + 324 + ... + 400 + 1), is 3,374.
hide answers
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Problem H5 | |
Consider the line Foot Length = Forearm Length + 4 (YL = X + 4).
a. | Complete the table below. |
b. | Determine the SSE for this data. |
When you click "Show Answers," the filled-in table will appear below the problem. Scroll down the page to see it.
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b. The SSE, (400 + 196 +... + 576 + 25), is 4,558.
hide answers
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Problem H6 | |
Compare the SSE in Problem H4 with the SSE in Problem H5. Which line provides a "better" fit? Explain.
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