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Topic: [ap-stat] explaining r^2
Replies: 1   Last Post: Nov 1, 2011 2:26 AM

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Erin Long

Posts: 26
Registered: 9/29/11
[ap-stat] explaining r^2
Posted: Oct 31, 2011 12:19 PM
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Based on the given Explanatory and Response Variables, I am trying to determine how to grade the explanation of r^2 on an exam. Here a few responses I received...

Explanatory variable = number of teaspoons of weed killer
Response Var = percent of weeds killed
r^2 = .972

1) 97.2% of the variation in the percent of weeds killed can be explained by the variation in the amount of weed killer used.

2) Approximately 97.2% of the percent of weeds killed can be explained by the strength of the weed killers on the field.

3) 97.2% of the variation in the percent of weeds killed can be explained by the linear relationship between the amount of weed killer used and the percent of weeds killed.

I taught the students to use #3, but I wasn't sure if #s 1 and 2 are acceptable as well.

Thanks in advance for the feedback!

Erin
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