Instruction: Discuss the sources of endogeneity and describe statistical methods to address it in econometric models.
Context: Candidates must demonstrate understanding of endogeneity issues in causal inference and proficiency in applying corrective methods.
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One common source of endogeneity is omitted variable bias, where we fail to include a variable that influences both the independent and dependent variables. Another source is simultaneity, where the causality between the independent and dependent variables runs in both directions. Lastly, measurement error in the variables can also introduce endogeneity.
To address endogeneity, a number of statistical methods can be applied, each suitable for different situations. One popular approach is the use of instrumental variables (IV). An instrumental variable is correlated with the endogenous explanatory variable but not with the error term, allowing us to isolate the variation in the explanatory variable that is not correlated with the error term. The two-stage least squares (2SLS) regression is a common method to implement IV estimation....