# Data Analysis

For some sampling goals, VSP allows the user to input the results of a sampling effort and obtain certain basic analyses of the data, including summary statistics, plots of the data, and results of statistical tests performed on the data. VSP provides a statement of the conclusion(s) that can be drawn based on results of the statistical tests. Only selected tests appropriate for the design in question are displayed. The tests included in VSP are standard statistical tests and are included in VSP for the convenience for the user so a separate software package for analyzing results in not needed. The tests and calculations used in VSP have been verified. This verification, along with an extensive discussion of the methods used in VSP, can be found in PNNL reports: Technical Documentation and Verification for the Buildings Module in the Visual Sample Plan (VSP) Software , PNNL -15202, June, 2005, and Version 2.0 Visual Sample Plan (VSP): Models and Code Verification , PNNL-13991, August 2002. If the user wants to perform more complex tests and analyses, a commercial statistical software package, or freeware such as EPA's ProUCL (ProUCL Version 3.0 User Guide April 2004, available for download from http://www.epa.gov/nerlesd1/tsc/tsc.htm) should be consulted.

There are currently four options: Data Entry, Summary Statistics, Tests, and Plots. Data Entry is a user input screen for inputting data values. Summary Statistics displays VSP calculations, shown in red, of selected summary statistics of the data input in Data Entry. The Tests tab displays the results of computations done within VSP to execute various tests and make various calculations.

#### The tests are of two types:

• Tests of the assumptions underlying the statistical tests (e.g., the normality assumption for the One Sample t test).

• Statistical tests to test the Null vs. Alternative Hypothesis for the sampling goal selected.

#### Calculations made by VSP are:

• Upper Confidence Limit (parametric and non-parametric) on the Mean and on Percentiles.

• A count of the number of sample points or grid locations that exceed the Action Level.

Output from VSP and the conclusion that VSP determines can be drawn based on the test results, and calculations are shown in red on the Tests screen. The Plots tab shows VSP-generated graphical displays of the data.

Not all sampling designs in VSP have the Data Analysis tab - either because analyzing sampling results is not a part of the sampling goal, or because VSP sponsors have not requested the VSP data analysis functionality.