Visual Sample Plan (VSP) is a software tool for selecting the right number and location of environmental samples so that the results of statistical tests performed on the data collected via the sampling plan have the required confidence for decision making. VSP provides sample designs and sample-size equations needed by specific statistical tests appropriate for several types of environmental problems. Below is a list of the sampling goals that can be addressed in the current version of VSP.
Compare Average to Fixed Threshold
Compare Average to Reference Average
Estimate the Mean
Construct Confidence Interval on Mean
Locate a Hot Spot
Show that at least some high % of area is acceptable
Combined Average and Individual Measurement Criteria
Detect a Trend
Identify Sampling Redundancy
Add Sample Locations
Compare Proportion to Fixed Threshold
Compare Proportion to Reference Proportion
Estimate the Proportion
Establish Boundary of Contamination
Find Target Areas and Analyze Survey Results (UXO)
Post Remediation Verification Sampling (UXO)
Sampling within a Building
Radiological Transect Surveying
Item Sampling
Non-statistical sampling approach
VSP is easy to use and highly visual. It has extensive online help and tutorial guides. Reports produced by VSP can be pasted directly into a quality assurance project plan or a sampling and analysis plan. VSP can be used to implement EPA's systematic planning process (EPA 2000) for a variety of problems: selection between clearly defined alternatives [Step 7 of the Data Quality Objectives (DQO) process], studies where a confidence interval on an estimated parameter is needed, or determination of whether a hot spot or target exists. The user specifies the criteria for "how good" the answer has to be (Step 6 of the DQO Process), and VSP uses this as input to the formula for calculating the required sample size. VSP is designed primarily for project managers and users who are not statistical experts, but individuals with statistical expertise also will find the code very useful.
For more information, please refer to chapter 1 of the VSP User's Guide.