New goods are at the heart of economic progress. But the value created by new goods must somehow be converted into an exact quantitative measure if official data on inflation, such as the Consumer Price Index, are to represent accurately the theoretical concept of a true "cost-of-living" index, and if official data are to capture the annual increase in output and productivity contributed by the invention of new goods as well as steady improvements in the quality of old goods. The eleven essays in this volume include historical treatments of new goods and their diffusion; practical exercises in measurement addressed to recent and ongoing innovations; and real-world methods of devising quantitative adjustments for quality change.