Assay Information

Use the Assay Information dialog (CHCHATTR GX) to view and change attribute information associated with assay data in a Geosoft database. To display and edit assay channel information, select the assay channel header cell in the open database and right-click Assay Attributes.

Assay Information dialog options

Assay name (channel name)	This is the name of the database channel.
Label	Optional label to be used when displaying the data on a map.
Units	Units of the assay (i.e. ppm), if known
Detection limit	The minimum analytic detection limit, if known. In the database, any values that are below the minimum detection limit are normally set to one-half the detection limit. If no detection level is given, then it is assumed to be equal to the smallest positive value in the channel.
Outlier limit	The cut-off for high-valued data outliers. Values larger than the outlier limit are set to this value. If no value is given, no limit is set.
Standard minimum Standard maximum	Minimum and maximum values to use in the Standards Report for determination of samples in and out of tolerance. If these values are not specified, the Standards Report reverts to using ± 2 standard deviations from the mean (or whatever value the user specifies there).
Logarithmic distribution	"Yes" to indicate the data is logarithmically distributed "No" to indicate the data is linearly distributed. Statistical and display tools in montaj Geochemistry will use this setting to determine the default way to deal with this data.
Symbol scaling (units/mm)	Scaling for symbols plotted in Geochemistry special symbol plots, including rose or sector plots (CHROSE GX), bar symbol plots (CHBAR GX). For instance, if this value is set to 50, a value of 250 will result in a rose plot sector with a radius of 5mm.
Assay method	The assay method, which is selected from a list of known assay methods in the file "ch_assay_method.lst" in the GEOSOFT directory. If the item typed in is not in the list, it will be added automatically. Use the "Assays" button to manage the list by adding or deleting items.
Class	The class identifier is used by various tools in Geochemistry to identify the type of channel. The following classes have special meanings in Geochemistry: Assay, Duplicate, Mask, Sample, Standard.

Application Notes

If you change any settings and click on OK, the changes will be saved in the database. If you select Cancel, the changes are not saved.

This option is run either for a single channel, by selecting the "Attributes" item after right-clicking the channel name in a database, or as part of the Set Attributes wizard, for all of the ASSAY channels, or all of the displayed ASSAY channels.

The detection limit is used in principal component analysis. If a value less than the detection limit is encountered, it is replaced by one-half the detection limit. This prevents, for instance, the calculation of the logarithm of a zero or negative number. If no detection limit is defined for a channel, then the smallest positive value found in the channel at run-time is used

The Assay Information option can only be run interactively.