问题


There is a single choice question about econometrics. Answer the question by replying A, B, C or D.
Question: Consider again the VAR model of equation 16. Which of the following conditions must hold for it to be said that there is bi-directional feedback?
A. The b and d coefficients significant and the a and c coefficients insignificant
B. The a and c coefficients significant and the b and d coefficients insignificant
C. The a and c coefficients significant
D. The b and d coefficients significant
Answer:

答案

模型 模型答案 正确答案
金声玉亮2.0 D. The b and d coefficients significant D
deepseekr1

To determine bi-directional feedback in a VAR model, both variables must influence each other. This requires the coefficients on the lagged values of each variable in the other's equation to be statistically significant.

Given the VAR model structure:
- **Equation for Y1**: \( Y1_t = a Y1_{t-1} + b Y2_{t-1} + \text{error} \)
- **Equation for Y2**: \( Y2_t = d Y1_{t-1} + c Y2_{t-1} + \text{error} \)

For **bi-directional feedback**:
- The coefficient \( b \) (effect of \( Y2_{t-1} \) on \( Y1_t \)) must be significant.
- The coefficient \( d \) (effect of \( Y1_{t-1} \) on \( Y2_t \)) must be significant.

**Analysis of options**:
- **A** and **B** incorrectly focus on own-lag coefficients (\( a \) and \( c \)) or mix own-lag and cross-lag terms.
- **C** only requires \( a \) (own-lag of \( Y1 \)) and \( c \) (own-lag of \( Y2 \)), which do not capture cross-variable feedback.
- **D** correctly identifies the cross-lag coefficients \( b \) and \( d \), whose significance confirms mutual influence between the variables.

**Answer**: D
D
gpto1 C D
GPT-4o C. The a and c coefficients significant D
llama3.1-70B-Instruct

C
D
llama3.1-405B-Instruct

C
D
DeepSeek-Coder-V2 D D
Qwen2-72B-Instruct D. The b and d coefficients significant D
baichuan4 D D
doubao D D
minimax C. The a and c coefficients significant D
kimi B. The a and c coefficients significant and the b and d coefficients insignificant D
wenxinyiyan D

Explanation:
In a VAR (Vector Autoregression) model, bi-directional feedback exists when both variables in the model influence each other. Consider a simple bivariate VAR(1) model as an example:

\(y_t = a_1 y_{t-1} + b_1 x_{t-1} + u_t\)
\(x_t = c_1 x_{t-1} + d_1 y_{t-1} + v_t\)

In these equations:

* \(y_t\) and \(x_t\) are the current values of the two variables.
* \(y_{t-1}\) and \(x_{t-1}\) are the lagged values of the two variables.
* \(a_1, b_1, c_1, d_1\) are the coefficients.
* \(u_t\) and \(v_t\) are the error terms.

For bi-directional feedback to exist, both \(y_{t-1}\) should influence \(x_t\) and \(x_{t-1}\) should influence \(y_t\). This means that the coefficients \(b_1\) and \(d_1\) should be significant. The significance of \(a_1\) and \(c_1\) is not directly related to bi-directional feedback; they represent the autoregressive effects within each variable.

Therefore, for bi-directional feedback, the condition that must hold is that the b and d coefficients are significant, which corresponds to option D.
D
zhipu D

For there to be bi-directional feedback in a Vector Autoregression (VAR) model, it means that each variable must be affecting the other variable. This requires that both sets of coefficients (those representing the influence of one variable on the other and vice versa) must be significant. Thus, if the b and d coefficients are significant, it implies that the influence runs both ways, indicating bi-directional feedback. Hence, the correct answer is D.
D
gpto1 C D