Reflected Stochastic Differential Equation Models for Constrained Animal Movement

Movement for many animal species is constrained in space by barriers such as rivers, shore-lines, or impassable cliffs. We develop an approach for modeling animal movement constrained in space by considering a class of constrained stochastic processes, reflected stochastic differential equations. Our approach generalizes existing methods for modeling unconstrained animal movement. We present methods for simulation and inference based on augmenting the constrained movement path with a latent unconstrained path and illustrate this augmentation with a simulation example and an analysis of telemetry data from a Steller sea lion(Eumatopias jubatus)in southeast Alaska.

In Praise of Ignorance

In this article Piero Formica examines the difference between incremental and revolutionary innovation, distinguishing between the constrained ‘path finders' and the unconstrained ‘path creators’. He argues that an acceptance of ‘ignorance’ and a willingness to venture into the unknown are critical elements in radically creative innovation and entrepreneurship.

Where Would the Federal Funds Rate Be, If It Could Be Negative?

In the wake of Great Recession, the Federal Reserve engaged in conventional monetary policy actions by reducing the federal funds rate. But soon the rate hit zero, and could go no lower. In such environments, policymakers still think in terms of where the federal funds rate should be, were it possible to go negative. To project the "unconstrained path" of the funds rate—ignoring the zero lower bound—and to identify the key underlying shocks driving that path, we employ a statistical macroeconomic forecasting model. We find that the federal funds rate would have been extremely negative during 2009-2010.