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| | CSE 291 Lecture Notes, February 22, 2005 |
 | | xbar is the exact mean of the training data, but it is not the exact mean of the population, so using xbar instead of mu can be called overfitting. |
 | | The alternative estimator with n under-estimates the true variance, so from a bias point of view, it overfits the training data also, and fits the population poorly. |
 | | This contrast illustrates that the concept of overfitting, while very important intuitively, is tricky to make precise. |
| www-cse.ucsd.edu /~elkan/291/feb22.html (710 words) |
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