QUESTION 5: Short Answer (4 POINTS) a. Briefly define heteroscedasticity. Which Gauss Markov assumption does it violate? Why would we be concerned about it in a model? What does it affect? What fix was discussed in the lecture and class that could be used in Stata (or other statistical software) to address it? (2 pts) b. Briefly define omitted variable bias. Which Gauss Markov assumption does it violate? Why would we be concerned about it in a model? What does it affect? (2 pts)