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小强爱英语 · 2023年06月06日

图看不明白

* 问题详情,请 查看题干

NO.PZ202208300200000304

问题如下:

Based on Exhibit 1, the initial results can be best described as being:

选项:

A.overfitted.

B.underfitted.

C.a good fit.

解释:

Solution

A is correct. The model predictive output, which is shown to be very non-linear, fits the training set too well and will not likely generalize well to new data, which is known as overfitting.

B is incorrect. An underfitted model would show a more linear output with multiple misclassifications between expected and actual results.

C is incorrect. A model with “good fit” would show a more linear output with some misclassifications between expected and actual results that have no defined pattern.

从哪里可以看出预测不准?另外这个图横纵坐标代表什么?

1 个答案

袁园_品职助教 · 2023年06月07日

嗨,努力学习的PZer你好:


从图上可以非常清晰的看出,该折线对于该数据集(training set)拟合的非常好。甚至出现了弯曲和非线性的现象。

由于未来用于预测的数据集的分布不可能和training set完全一样,所以可以把training set完美分割的很好的折线是无法用在out-of sample data或预测未来上的。

对于training set拟合近乎完美,做预测却非常不准的现象即为Overfitting。

这张图没有横轴纵轴坐标,也不需要知道这个数据的含义,只要看到这个预测出来的折线是歪歪扭扭的,完全按照数据集来的,就是过度拟合哦

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