General unrestricted models (GUMs) may include important individual determinants, many small relevant effects, and irrelevant variables.  Automatic model selection procedures can handle perfect collinearity and more candidate variables than observations, allowing substantial dimension reduction...

Even in scientific disciplines, forecast failures occur.  Four possible states of nature (a model is good or bad, and it forecasts well or badly) are examined using a forecast-error taxonomy, which traces the many possible sources of forecast errors.  This analysis shows that a valid model can...

Success in accurately forecasting breaks requires that they are predictable from relevant information available at the forecast origin using an appropriate model form, which can be selected and estimated before the break.  To clarify the roles of these six necessary conditions, we distinguish...