Simultaneous causality bias:

Question

BlackTom AI · Accepted Answer

Simultaneous causality occurs when X and Y affect each other: X → Y and Y → X. This two-way causal link makes X endogenous in the regression of Y on X, violating the OLS assumption that regressors are uncorrelated with the error term and leading to biased and inconsistent OLS estimates.

Relevant knowledge points:
- OLS consistency requires E[X·u] = 0 (no correlation between regressor and error).
- Reverse causality (Y → X) creates endogeneity: X is partly determined by Y, which depends on the error term in the structural equation for Y.
- Simultaneous equations can be written in structural form and solved to see the induced correlation.
- Bias arises because OLS attributes all X–Y covariance to the coefficient on X, not to the mutual causation.

Step-by-step reasoning with equations:
1. Structural equations: Y = βX + u (equation of interest), and X = γY + v (feedback equation).
2. Substitute Y into X: X = γ(βX + u) + v = γβX + γu + v.
3. Rearrange: X(1 − γβ) = γu + v.
4. Solve for X: X = [γ/(1 − γβ)]u + [1/(1 − γβ)]v.
5. This representation shows X contains a component proportional to u. Therefore Cov(X, u) = [γ/(1 − γβ)]Var(u) + Cov(v, u)/(1 − γβ). Unless γ = 0 and Cov(v,u)=0, Cov(X,u) ≠ 0.
6. Nonzero Cov(X,u) violates OLS exogeneity; OLS estimator is biased and inconsistent.

Why the correct choice is correct:
- The chosen option explicitly states the defining feature of simultaneous causality: a causal link from Y back to X in addition to X → Y, which is precisely the source of endogeneity and bias.

Why other options are incorrect:
- "Is also called sample selection bias": sample selection bias arises from nonrandom sampling, not from mutual causation.
- "Results in biased estimators if there is heteroskedasticity": heteroskedasticity does not bias OLS coefficients (it affects standard errors and efficiency); it is not the cause of simultaneous causality bias.
- "Happens in complicated systems of equations called block recursive systems": block recursive (recursive) systems are ordered so no simultaneity/reverse causation exists; simultaneity arises in nonrecursive systems.

Conclusion: The correct answer states that simultaneous causality arises when, besides X → Y, there is a causal link Y → X; this matches and confirms the provided answer.

Simultaneous causality bias:单项选择题

类似问题

Which of the following parameters is used to determine the concentration of protein in a spectrophotometer?

What are the units of absorbance?

What is the concentration of protein in the stock solution of BSA used for the standard curve?

When dissolved in water, hydrogen bromide (HBr) forms hydrobromic acid. Determine the hydroxide ion concentration in a 4,500 mL solution containing 3.78 g hydrogen bromide; K = 1.00 x 10¯14.

UVA radiation has a wavelength of approximately 390. nm. What is the energy of a photon of this light? (Planck's constant is 6.626 x 10 − 34 J s)

A student wants to prepare exactly 350. mL of a 0.2750 M aqueous potassium nitrate solution. What mass of potassium nitrate (molar mass = 101.11 g/mol) must the student dissolve in the 350. mL of solution?

What do the "big six" polymers have in common?

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单