We present a two-armed bandit model of decision making under uncertainty where the expected return to investing in the "risky arm'' increases when choosing that arm and decreases when choosing the "safe'' arm. These dynamics are natural in applications such as human capital development, job...

We provide a macroeconomic theory where demand for goods has a productive role. A search friction prevents perfect matching between producers and potential customers. Larger demand induces more search, which in turn increases GDP and measured TFP. We embed the product-market friction in a...

We study a model of collective search by teams. Discoveries beget discoveries and correlated search results are governed by a Brownian path. Search results' variation at any point---the search scope---is jointly controlled. Agents individually choose when to cease search and implement their best...

What makes an asset institutional-quality? This paper proposes that one reason is the existing concentration of delegated investors in a market through a liquidity channel. Consistent with this intuition, it documents differences in investor composition across US cities and shows that delegated...

A decision maker constructs a convex set of nonnegative martingales to use as likelihood ratios that represent parametric alternatives to a baseline model and also non-parametric models statistically close to both the baseline model and the parametric alternatives. Max-min expected utility over...

This paper introduces a method for solving numerical dynamic stochastic optimization problems that avoids rootfinding operations. The idea is applicable to many microeconomic and macroeconomic problems, including life cycle, buffer-stock, and stochastic growth problems. Software is provided

We introduce a novel simulated certainty equivalent approximation (SCEQ) method for solving dynamic stochastic problems. Our examples show that this method only requires a desktop computer to solve high-dimensional finite- or infinite-horizon, stationary or nonstationary dynamic stochastic...

We propose a model that starts from the premise that intangible capital needs to be stored on some medium --- software, patents, essential employees --- before it can be utilized in production. Storage implies that intangible capital may be partially non-rival within the firm, leading to scale...

Contrary to the Black-Scholes model, volatilities implied by index option prices depend on the exercise price of the option and are often higher than realized volatilities. We explain both facts in the context of a model that can also explain the mean and volatility of equity returns. Our model...

This paper studies the pricing of volatility risk using the first-order conditions of a long-term equity investor who is content to hold the aggregate equity market rather than tilting towards value stocks and other equity portfolios that are attractive to short-term investors. We show that a...