The OLS Estimators of the Coefficients in Multiple Regression Will $Y _ { i }$

Short Answer

The OLS estimators of the coefficients in multiple regression will have omitted variable bias a. only if an omitted determinant of $Y _ { i }$ is a continuous variable.
b. if an omitted variable is correlated with at least one of the regressors, even though it is not a determinant of the dependent variable.
c. only if the omitted variable is not normally distributed.
d. if an omitted determinant of $Y _ { i }$ is correlated with at least one of the regressors.