For the 2-semester principles of economics course. Reviewers tell us that Case/Fair is one of the all-time bestselling POE texts because they trust it to be clear, thorough and complete. This well-respected author team is joined for the 9th edition by a new co-author, Sharon Oster. Sharon's research and teaching experience brings new coverage of modern topics and an applied approach to economic theory, as demonstrated in the new Economics in Practice feature.