Applying survey research methods to account for denied access to research sites on private property

Abstract

Needs for environmental information have led to more emphasis on surveys that assess changing environmental conditions. In order to obtain biological, physical, and chemical measures of environmental change, it is critical to obtain repeated access to research sites. Use of established survey methodology can improve access rates to private property in order to visit randomly selected research sites. Surveys initiated by the U.S. Environmental Protection Agency’s Environmental Monitoring and Assessment Program (EMAP) were conducted in 1995 and 1996 in Eastern North Dakota to monitor environmental conditions in prairie wetlands. These surveys required written permission from landowners to access private property. A summary of survey research methods designed to improve access rates to sites on private property is presented. Approximately 20% of the landowners who granted access did so in response to telephone calls after attempts by mail failed. The data show that a disproportionate number of accessible sites were located on non-agricultural lands, particularly in 1996. Owners of sites where agricultural land abutted wetlands tended to deny access. This may introduce bias in the monitoring data. A weighting class adjustment procedure was applied to account for any nonresponse bias resulting from denied access. This procedure deals with the imbalance from denied access and at least partially returns a balance to the collected data.