What is an economic theory or model? What constitutes a "good" economic theory or model? What is the difference between positive and normative economics? How can knowledge of positive economics be useful in normative economics? Discuss the three fundamental economic questions that all nations must address. Interpret what an increase in demand and an increase in supply mean. Discuss the causes of an increase in demand and an increase in supply. How are increases in demand and supply expressed graphically? Explain why the market price may not be the same as the equilibrium price. Explain the statement "People respond to incentives and disincentives" in relation to the demand curve and supply curve for good X