Weak instruments can produce biased IV estimators and hypothesis tests with large size distortions. But what, precisely, are weak instruments, and how does one detect them in practice? This paper proposes quantitative definitions of weak instruments based on the maximum IV estimator bias, or the...

"Open interest, or the amount of contracts outstanding in futures markets, has remarkable power to forecast commodity, currency, bond, and stock prices. Changes in open interest are highly pro-cyclical and predict asset-price fluctuations better than a number of alternative variables including...

"We develop a life-cycle consumption and portfolio choice model in which households have nonhomothetic utility over two types of goods, basic and luxury. We calibrate the model to match the cross-sectional and life-cycle variation in the basic expenditure share in the Consumer Expenditure...