Empirical tests for bubbles typically focus on the stationarity properties of the dividend yield. Evidence of nonstationarity in the dividend yield is viewed as proof of bubbles, while stationarity is interpreted as absence of bubbles. For economies with arbitrary pricing kernels but stationary...

This paper proposes a new unit-root test for the case where a high-dimensional vector of nonstationary time series is considered. A new CLT is being established and studied both theoretically and numerically

While differencing transformations can eliminate nonstationarity, they typically reduce signal strength and correspondingly reduce rates of convergence in unit root autoregressions. The present paper shows that aggregating moment conditions that are formulated in differences provides an orderly...

Dynamic equilibrium models are specifted to track time series with unit root-like behavior. Thus, unit roots are typically introduced and the optimality conditions adjusted. This step requires tedious algebra and often leads to algebraic mistakes, especially in models with several unit roots. We...