Trend Analysis

You can use this function to calculate basic statistical parameters for one or more Surpac string files.

To run this function: Choose Block model > Geostatistics > Trend analysis, or...

In the Function Chooser, type TREND ANALYSIS, and press ENTER.

Data string files for this module may come from any source. There must be a minimum of 4 samples after constraints have been applied to calculate the Median Absolute Deviation (MAD). If there are less than 4 samples, "Not calculated" appears in the report.

Typically the data points have 3D coordinate positions (which may be used to constrain the selection of data to be used), however this is not essential because the distributions and statistics are calculated on the contents of one or more of the description fields within the string file, for example D1 or D2.

The physical location of the data points with respect to each other is not taken into account, and the results should be interpreted accordingly. For instance, frequency distributions may be meaningless if drill hole data points are located on a 10 metre grid in the high grade area and on a 100 metre grid in the lower grade areas. It is also important that the data to be processed is of a constant support size.

Procedure

Choose Geostatistics > Trend Analysis.

You will see the

Main tab on the Trend Analysis form.

Form Feature	Description
Output Report File	If the Output Report File Name field is left blank, the results are output only to the screen. Created output files can have the following formats: .not (Surpac Note File), .csv (Comma Separated), .htm (Hypertext Markup Language), .html (Hypertext Markup Language), .rtf (Rich Text Format), .pdf (Adobe Acrobat) and *.ps (Postscript).
Location, Id range, String range	Files may be selected using the combo box or entered directly. You can select multiple files using the Id range, i.e. File name d_sec.str, Id range 1,3, 1 would generate statistical values for each file (d_sec1.str, d_sec2.str and d_sec3.str). This is different to basic statistics where the values in each file would be combined and only one statistical analysis done on the combined values.
D Field, Name, Min. value, Max. Value	Description fields (D1 - D100) to be processed as variables. Options are available for naming the description fields for reporting and display purposes, An example Name value is 7250-7300 ppm Au. You can also constrain the samples selected to those whose values lie between specified minimum and maximum values. If minimum and/or maximum values are unspecified (i.e. left blank) no minimum and/or maximum value constraints are applied as appropriate. For example, if neither a minimum nor a maximum value is specified, all samples are selected.
Percentile Range	Desired percentile values can be entered either as a range, 30,60,10, as intervals, 30;40;50;60 or as a combination 30,50,10;60. These would have the percentile values for 30, 40,50 and 60 calculated. Percentiles are described more fully in basic statistics. A warning message "Warning: Smallest percentile that can be calculated with this data set is 12.051" indicates that one of the statistical methods could not be performed correctly i.e. any statistical calculation that uses a percentile value less than 12.051 may be incorrect (the alpha test uses a percentile value of 10). This will only happen for very small data sets.

If you wish to constrain the data by coordinates, click the Co-ordinate Constraints tab.

You will see the

Co-ordinate Constraints tab on the Trend Analysis form.

Fill in the fields on the Trend Analysis form.
Click Apply.