Unformatted text preview: (1.) (8 points) What does R2 represent with respect to simple linear regression and how
can it be used as a metric tojudge whether a simple linear regression is “good”? R2 represents the percentage of variation in the Y variable explained by the X variable in
a regression equation. It ranges from 0% to I 00%. The larger the R2, the higher the
percentage of variation in Y explained by X, and the better the regression equation. (2.) You have randomly sampled 28 sugar maple trees in the Smithers Forest and
measured the amount of sapﬂow (in gallons) each produced. The mean of your sample of
28 observations was 13.2 gallons and the standard deviation was 4.5 gallons. (a.) (4.5 points) Please correctly calculate a 95% conﬁdent interval for the mean of your
sample. Be sure to write your ﬁnal answer appropriately and include units. ii(tvalue><i]: l3.2i(2.052x£] =13.2i1.7451 J; m [11.46, 14.95] gallons (b.) (4.5 points) Correctly interpret your interval in the context of this problem. BE
PROBLEM SPECIFIC. I am 95% conﬁdent that the interval [ 11.46 , 14.95] gallons contains the true average
gallons of sapﬂow per sugar maple tree in the Smithers Forest. FOR 321 Practice Test 3 Answers ...
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 Spring '07
 DORUSKA

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