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🌊 梅根 · 2020年02月25日

问一道题:NO.PZ2020010801000002

问题如下:

You suspect that the CAPM held on all days except those with a Federal Open Markets Committee (FOMC) announcement, and on these days the β\beta is different. How can a dummy be used to capture this effect? What could you do if you suspected that both a and b are different on FOMC days?

选项:

解释:

The model that allowed differences in the slope would be Ri=α+βRm,i+γIFOMCRm,i+ϵiR_i = \alpha + \beta R_{m,i} + \gamma I_{FOMC} R_{m,i} + \epsilon_i where IFOMCI_{FOMC} is 1 on FOMC days and 0 otherwise. If γ\gamma is not zero, then the slope is different on FOMC days. This can be extended to both parameters by estimating the model

Ri=α+γIFOMC+βRm,i+γIFOMCRm,i+ϵiR_i = \alpha + \gamma I_{FOMC}+\beta R_{m,i} + \gamma I_{FOMC} R_{m,i} + \epsilon_i

and on these days the β is different. How can a dummy be used to capture this effect?

为什么不可以像以下引入dummy variable 呢?

Ri=α+β*γIFOMC*Rm,i​+ϵi

1 个答案

品职答疑小助手雍 · 2020年02月26日

同学你好,这样非FOMC日只剩下常数项了没法做回归啊。