A master sample is essentially a list of sites needed for a complete census of an area of interest and a list of attributes assigned to each site. A master sample can be created using the Generalized Random-Tessellation Stratified (GRTS) technique, which creates the list of sites but also retains randomization and spatial balance if the full list of sites is subset for sampling. Because conducting a complete census is often cost prohibitive, a master sample for an area of interest can be used to select a randomized, spatially balanced set of representative sampling locations (for more comprehensive materials about master sample details, please see the references listed at the end of this summary). The master sample concept, along with other monitoring and monitoring design tools, has broad applicability to address status and trends questions in the estuarine and near shore marine areas (area-based master sample), in addition to the status and trends of attributes along linear stream networks.
As part of the Integrated Status and Trends Monitoring (ISTM) effort, PNAMP (through Oregon State University) developed a prototype web-based master sample tracking and management system to support the ISTM demonstration for the lower Columbia ESU. The next step is to fully develop this tool into a regional resource that can support the interests of increasing numbers of users in drawing samples from this population domain. This system will allow users to know who else has selected sites from the master sample covering stream networks in their domains; to design individual or integrated monitoring programs; to know how existing sites relate to a common master sample; and what they are collecting at the site over time.
In the fall of 2011, PNAMP convened a working group to evaluate the prototype and develop requirements for a regional tool. PNAMP will continue to receive feedback from potential users while initiating development of the tool for regional accessibility and use in early 2012. Development will be iterative and occur over several months. It is also intended that the tool will be integrated with MonitoringMethods.org, proposed metadata tools, and Columbia Habitat Monitoring Program (CHaMP) tools, as appropriate.
For more details about the master sample concept, please see:
Larsen, D.P., A.R. Olsen, and D.L. Stevens. 2008. Using a master sample to integrate stream monitoring programs. JABES 13: 243-254.
Stevens, Jr., D.L. and A. R. Olsen. 2004. Spatially-balanced sampling of natural resources. J. American Statistical Association 99: 262-278.
Stevens, Jr., D.L., D. P. Larsen, and A. R. Olsen. 2007. The role of sample surveys: why should practitioners consider using a statistical sampling design? pp 11-24 in D. H. Johnson, B. M. Shrier, J. S. O’Neal, J. A. Knutzen, X. Augerot, T. A. O’Neill, and T. N. Pearsons. Salmonid field protocols handbook: techniques for assessing status and trends in salmon and trout populations. American Fisheries Society, Bethesda, MD.