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xīnyí · 2024年07月02日

overfitting

NO.PZ2023010903000045

问题如下:

Leeter tells Clickman about the interesting investment process of the XTZZ Fund. Leeter states that many times, government- reported data are revised three to six months after the data are initially reported. These revisions then become incorporated into the historical data, with the revised value replacing the originally reported value. When the revision is incorporated, the data are referred to as “clean data.” XTZZ applies its analysis in a manner in which the originally reported data exist as a lagged factor until the revised data become available. This approach differentiates XTZZ from funds that use only the “clean” data, which ignore the initially reported data values.

XTZZ’s approach to analyzing government-reported data most likely reduces:

选项:

A.

look-ahead bias

B.

survivorship bias

C.

model overfitting

解释:

XTZZ’s approach prevents the use of “revised” government data that are not known when the data are initially reported. By not incorporating revised government data until they are actually revealed, XTZZ reduces look-ahead bias.

B is incorrect. Survivorship bias occurs when analysis on past data ignores firms that have ceased to exist at some point during the analysis period.

C is incorrect. Model overfitting occurs when the model fits the past data by finding a pre-conceived relationship (i.e., making the model specifications biased toward the pre-relationship) or when the model is biased toward patterns that are specific only to the past data.

老师,可以再解释一下overfitting bias吗


1 个答案

笛子_品职助教 · 2024年07月03日

嗨,努力学习的PZer你好:


overfitting bias也是统计学里的一个概念:过度拟合。

过度拟合是指:针对一段历史数据,充分利用历史数据里的特定规律,来制定某个策略。

但历史数据里的特定规律,并不一定在未来还会重现。这些特定的规律,可能只适用于这一特殊的历史时期。

因此,根据这一段历史数据做出来的策略,并不一定能够在未来获取收益。

这是过度拟合的含义。

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