Creating a Scattergram of Observed Data v Grid Values

RockWorks | Utilities | Grid | Stats | Krajewskigram

Use this program to create an XY plot or scattergram of observed Z values versus computed node Z values for corresponding locations in an existing grid model (".RwGrd" file).

! This tool requires that the source data, from which the grid model was computed, be displayed in the RockWorks Utilities data sheet so that source data can be compared to the gridded data.

Menu Options
Step-by-Step Summary

Menu Options

• Input Columns:  
  • X (Easting), Y (Northing): Select the columns in the main data sheet that contain the X and Y location coordinates for the source data, from which the grid model being analyzed was generated.
  • Z (Elevation): Select the data sheet column that contains the original Z values that are modeled in the grid model. These source Z values will be plotted along the X axis, against the computed node values. 
• Grid Model: Click on this item to select the name of the existing grid file, created from the data in the main data sheet, whose node values are to be displayed against the source Z values in the scatter plot. 
• Symbols: Click on the sample to select the desired symbol style and color.
• Symbol Size: Click to establish the size of the symbols, as a percent of diagram width. 
• Border Annotation: Insert a check here to activate the plotting of titles, ticks, and labels along the horizontal and vertical axes. Expand this item to access the settings. 
  • Left/West Axis, Right/East Axis, Basal/South, Top/North Axis: Insert a check in any of these check-boxes to activate their plotting. Expand each item to access common settings: 
    • Ticks: To turn tick marks on for any activated axis, insert a check in the appropriate check-box. Expand the Ticks to set size (as a percent of the diagram width) and color. 
    • Labels: To turn labeling on for any activated axis, place a check in the appropriate check-box. Expand this heading to set label angle, size (as a percent of the diagram width), color, and font type.  
    • Titles: To turn titles on for any activated axis, place a check in the appropriate check-box. Expand Titles to enter the text to be plotted for the title, and to set label angle, size (as a percent of the diagram width), color, and font type.
    • Subdividers: Expand this to turn on/off the plotting of a horizontal and/or vertical grid of lines, at major and minor intervals. Once activated, expand the items to choose the colors and line styles for the selected grids. 
• Manual Ranges: Insert a check in this box if you want to establish a range of data for the diagram that is either less than the actual data values (to filter the data), or greater than the actual data values (to extend the axes for comparing different data sets).  If the Manual Ranges check-box is left blank, the program will use all scanned data and dimension the X and Y axes to accommodate those data.  Expand this item to enter the desired ranges.  
  • X Minimum, X Maximum: Click on these items to type in the minimum and maximum data values to be represented for the X axis (observed values).. 
  • Y Minimum, Y Maximum: Click on these items to type in the minimum and maximum data values to be represented for the Y axis (grid model values).
• Manual Subdivision: Insert a check here to override the program-computed axis labeling intervals. Expand this item to access settings. 
  • X Minor: Type in the interval for the X axis at which small tick marks are to be plotted. 
  • X Major: Enter the X axis interval at which major tick marks and labels are to be plotted. This must be an even multiple of the X Minor setting. 
  • Y Minor: Type in the interval for the Y axis at which small tick marks are to be plotted. 
  • Y Major: Enter the Y axis interval at which major tick marks and labels are to be plotted. This must be an even multiple of the Y Minor setting. 
• Diagram Dimensions: Expand this item to enter the height and width of the diagram. These values would typically represent inches, however note that you can scale the diagram both larger and smaller for both screen display and printer output in the RockPlot2D plotting window. 

Step-by-Step Summary

1. Access the RockWorks Utilities program tab. 
2. Open the XYZ data from which the grid model was created.  This is necessary because the program needs to know the original observed values against which the grid model values will be compared.
   • If the grid model was created in the Utilities, the original data was probably stored as an .RwDat file; you can use the File | Open option to access that file, or open it via the Project Manager.
   • If the grid model was created in the Borehole Manager, you can transfer the original data to the Utilities datasheet for use with this program, using several methods:
     • For elevations at the top of the well, use the Borehole Manager's File | Transfer | Locations -> Utilities Datasheet option to transfer Location tab data to the Utilities datasheet.
     • For stratigraphic elevations, use the Borehole Manager's File | Export | Stratigraphy Data -> Utilities Datasheet option to transfer stratigraphic data to the Utilities datasheet.
     • For water level data, use the Borehole Manager's File | Export | Aquifer Data -> Utilities Datasheet tool to transfer water level data to the Utilities datasheet.
3. Select the Grid | Statistics | Krajewskigram menu option. 
4. Enter the requested menu settings, described above.
5. Click on the Process button to create the scattergram. 

The program will read the original data values from the main data sheet. It will determine the calculated grid model Z-values for each control point location and create an X,Y scattergram of observed versus calculated Z-values. It will include a best-fit line through the points, and post the correlation coefficient.  This number ranges between zero (no correlation) to 1.0 (perfect correlation).  Note: The correlation coefficient provides a quantitative comparison between the observed data and the predicted model. It does not reflect how reasonable the model is.  The diagram will be displayed in a RockPlot2D tab in the Options window.

6. You can adjust any of the settings in the Options window and then click the Process button again to regenerate the diagram.
7. View / save / manipulate / export / print the diagram in the RockPlot2D window. 
   
   

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