RockWorks | ModOps | Grid | Directional | Trend Surface Report
Use this program to determine regional trend for selected data in the main data sheet. This can help you to determine what trend order to select when creating a Trend Surface grid model, and it can help you to isolate regional anomalies by computing trend residuals.
- This program - Trend Surface Report - performs a trend surface analysis on a selected Z-value column in the data sheet and lists the correlation and residuals for first through sixth order polynomials in a report. The completed report can be output to a RwDat file, CSV, Text, or RTF.
- A companion program - Trend Surface Residuals - performs a trend surface analysis on a selected z-value column and computes the residuals for a selected polynomial order, representing the difference between observed z-values and trend z-values. The residuals are stored in a data sheet column of the user’s choice. See Computing Trend Surface Residuals for details.
Menu Options
Step-by-Step Summary
- Data Columns: Select the input data by clicking on this tab.
- X (Easting), Y (Northing): Select the columns in the data file that contain the X and Y coordinates for the sample sites.
- Z (elevation): Select the column that contains the data to be analyzed.
- Output Options
Click this tab to define the output format(s) for the report. (More info)
- RwDat (RockWorks): Click in this button if you want the report generated in a RockWorks datasheet (.RwDat) format.
- CSV (Excel): Click in this button if you want the report generated in a CSV file format for use in Excel.
- TXT (Notepad): Click in this button if you want the report generated in a text (.txt) format.
- RTF (Word): Click in this button if you want the report generated in an RTF file format for use in Word.
- Access the RockWorks Datasheet program tab.
- Enter/import your data into the datasheet. This program requires that you have a data set containing multiple sample sites with X and Y coordinates and a Z value of some kind for which the trend surface will be computed.
- Select the ModOps | Grid | Directional | Trend Surface Report menu option.
- Enter the requested input settings, as described above.
- Click the Process button to continue.
The program will compute first through sixth order polynomials for the selected data, and display the completed report within the requested output window(s). Click here to see a sample report.
The report can be used to determine how well any of the trend surface models fit your data. The higher the correlation coefficient, the better the fit. This information can be helpful in determining whether there is much regional trend to your data. By isolating regional behavior, local anomalies can stand out.
This report can also be helpful if you are creating a trend surface map of your data, by providing correlation information. See Trend Surface Gridding for information about creating trend surface maps, and examples of different polynomials.
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