We consider the bootstrap method for the covariates augmented Dickey-Fuller (CADF) unit root test suggested in Hansen (1995) which uses related variables to improve the power of univariate unit root tests. It is shown that there are substantial power gains from including correlated covariates....

This paper relates physical and mental health status to labor force participation and compares these relationships among self-report and proxy respondents. Previous research has conjectured that self-reports of health status may lead to an upward bias in the estimated effect of health on labor...

This paper explores a relatively new methodology, the directional distance function method, to analyze productivity growth. The method explicitly evaluates the role undesirable outputs of the economy, such as carbon dioxide and other green-house gases, have on the frontier production process...