Comparison Levels

 

See Also:

Confidence Interval

Parametric Tolerance Interval

Threshold Report

Time-Concentration Graph

Import File Format

Multiple Well Time Series Graph

 

This dialog allows you to specify comparison levels (such as MCL) for parameters. Comparison levels are used in the statistical tests listed above. Comparison levels specified in this dialog take precedence over comparison levels specified in the import file. Comparison levels specified in this dialog are also available for every data file.

 

Comparison levels are parameter specific values such as MCLs or site specific action levels. These are compared to a statistical value calculated from measured concentrations. The following tests make use of comparison levels:

 

 

There are two ways to set comparison levels for parameters.

 

1. If your original database includes a comparison level with each concentration, that comparison level can be imported into ChemStat. ChemPoint and USEPAGRITS/STAT both can include comparison levels with parameter concentrations. The Universal Converter program also supports import or conversion of comparison levels with parameter concentration. In the case of multiple comparison levels, the most recent level specified is used for each parameter. For more information on importing comparison levels, refer to Import File Format in the ChemStat on-line help.

 

2. Within ChemStat, you can specify or change a comparison level for any parameter. Select Comparison Levels from the Options menu. The dialog will display a list of parameters and their comparison levels. Click the Add New button to add a new comparison level. If there is a current project open in ChemStat, names of all parameters in the project will be available for selection. Select or enter a parameter name and enter the comparison level. Remember that ChemStat converts all concentrations to ppb, so be sure to enter the comparison level in ppb if appropriate.

 

Important: When you specify comparison levels using this procedure, they will be available with each ChemStat session, and will be available for every project. If a parameter comparison level is specified in both the import file and from the Comparison Levels dialog, the value in the Comparison Levels dialog takes precedence.