This sub-page of the Data Analysis page displays results of specific tests on the data values from the Data Entry Sub-page.
This page contains the following controls / displays:
Normal Distribution Test |
VSP conducts a Shapiro-Wilk normality test if there are fewer than 50 selected data values; otherwise a Lilliefors normality test is conducted. |
Satterthwaite's t-Test |
When the Survey Unit sample variance is significantly different from the Reference Area sample variance, VSP conducts the Satterthwaite's t-Test to compare the mean against a reference mean for the selected data set. The test can only be conducted when data from a Survey Unit is selected. |
Two Sample t-Test |
When the Survey Unit sample variance is approximately equal to the Reference Area sample variance, VSP conducts the Two-Sample t-Test to compare the mean against a reference mean for the selected data set. The test can only be conducted when data from a Survey Unit is selected. |
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.