Regional economic impacts of public recreation facilities are caused by purchases made by households during trip production. Purchases are made near home, en route, or near the recreation site. Locations where en route purchases are made are particularly ill-defined. Surveys that gather trip expenditure data usually only collect home and site locations and travel mileage, with no reference to the actual route taken to the recreation site or where en route purchases are made. The elliptic method uses current survey data to estimate the amount of en route purchases made in any location as a function of the likelihood of travel through that location. The purchase estimates are then aggregated at the level of counties or groups of counties designated in the economic impact analysis.
English, Donald B.K.; Thill, Jean-Claude. 1996. Assessing Regional Economic Impacts of Recreation Travel from Limited Survey Data. Res. Note SE-2. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southeastern Forest Experiment Station. 8 p.