Typical panel data models make use of the assumption that the regression parameters are the same for each individual cross-sectional unit. We propose tests for slope heterogeneity in panel data models. Our tests are based on the conditional Gaussian likelihood function in order to avoid the...

This article examines the relationship between Research & Development (R&D) funding and the production of knowledge by academic chemists. Using articles published, either raw counts or adjusted for quality, we find a strong, positive causal effect of funding on knowledge production. This effect...

This article considers testing the significance of a regressor with a near unit root in a predictive regression model. The procedures discussed in this article are nonparametric, so one can test the significance of a regressor without specifying a functional form. The results are used to test...

As patent applications increase, and the range of patentable technologies increases, the length of time it takes for an invention to go through the examination process at the U.S. Patent Office has increased. Concerns over the distributional effects of these changes have been expressed during...

The impacts of two recent changes in US patent policy depend on the length of time it takes for an invention to go through the examination process. Concerns over the distributional effects of these changes were expressed during policy debates. We use data on U.S. patent applications and grants...

We introduce a new weekly database of spot and forward US-UK exchange rates as well as interest rates to examine the integration of forward exchange markets during the classical gold standard period (1880-1914). Using threshold autoregressions (TAR), we estimate the transactions cost band of...

Several widely used tests for a changing mean exhibit nonmonotonic power in finite samples, due to "incorrect" estimation of nuisance parameters under the alternative. In this paper, we study the issue of nonmonotonic power in testing for changing mean. We investigate the asymptotic power...