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Unformatted text preview: test score is the average. (c) Given that homework does not come into the model, an additional hour of homework has no impact on the test scores. (d) One way to determine this is to look at the formula for R 2 . We know that R 2 = SSE/SST . For now, all we need to show is the numerator. SSE = P n i =1 ( b y i − y ) 2 . As we noted above, the coe ﬃ cient on c (1) is simply the mean of y ( y ). Therefore, the f tted value b y i = y for all i . Hence, SSE = 0 and thus R 2 = 0. (e) R 2 is a measure of how well the x explains the y . If there is no x in the model, then it cannot explain y . 2...
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- Fall '08
- Econometrics, Trigraph, Yi, i=1, ] xi =