A question on causal inference, problems of omitted variable

bias and measurement error. see below please

Consider the following simultaneous, two equation model of demand and supply in an agricultural market. Demand Function: Q? = do + a1P; + azle + uit (1) Supply Function: Qt = Bo + B1Pt + u2t (2) where Q? is the quantity demanded, Q; is the quantity supplied, Pt is price, It is consumer income, and can be considered as predetermined or 'exogenous'. The terms uit and uzt are the error terms for each equation. (a) What is the best way to interpret the data on prices and quantities we observe for data based on this system? Does the observed data reflect information on a single set of demand and supply curves? Draw diagrams to illustrate your answer. (4 marks) (b) Next, suppose we added another variable, wealth R , to the demand equation. What implication does this have for our attempt to identify the supply equation? (6 marks)2. (a) Compare and contrast the econometric problems of omitted variable bias and measurement error. In particular, comment on the direction of bias in our estimates that is created by these problems. (5 marks). (b) Does omitted variable bias always result in an upward bias? Explain