The purpose of this option is to make available some of VSP's useful features, such as overlaying sampling locations on a site map and exporting sampling coordinates to a text file, even when a desired sampling design is not yet incorporated into the program. Please consult EPA's guidance document, Guidance for the Data Quality Objectives Process (EPA. 2006a), to put user-supplied sampling designs into the context of environmental decision-making.
Before deciding to develop a sampling plan based on a user-supplied sampling design, consider the assumptions and limitations involved. For examples of assumptions, limitations, and details for a variety of statistical tests, please consult Data Quality Assessment: Statistical Methods for Practitioners (EPA. 2006b). This document, as well as the DQO guidance document, is currently available at: http://www.epa.gov/quality/qa_docs.html
VSP does not provide any equation for this option. The user must supply the number of samples based on considerations specific to the problem at hand. Note that VSP provides the random sampling locations, thus this option removes the bias associated with the human sampler selecting the locations, such as occurs in judgmental sampling.
EPA. 2006a. Guidance on Systematic Planning Using the Data Quality Objectives Process. EPA QA/G-4, EPA/240/B-06/001, U.S. Environmental Protection Agency, Office of Environmental Information, Washington DC.
EPA. 2006b. Data Quality Assessment: Statistical Methods for Practitioners. EPA QA/G-9S, EPA/240/B-06/003, U.S. Environmental Protection Agency, Office of Environmental Information, Washington DC.
The design page is essentially the same as the Sample Placement Page of most other designs, with the addition of: