The gravity model is the workhorse model to describe and explain variation in bilateral trade patterns. Consistent with both Heckscher-Ohlin models and models of imperfect competition and trade, this versatile model has proven to be very successful, explaining a large part of the variance in...

The values of goods and services provided by natural and constructed wetlands are examined through a meta-analysis of 418 observations of the economic value of 186 wetlands. Water quality improvement, non-consumptive recreation, and provision of natural habitat and biodiversity turn out to be...