Reports
Surfer can generate several types of detailed grid reports. This table provides a snapshot of the types of information produced for each report type. Descriptions of the report sections are below the table.
If you make changes to the data selection (i.e. changing a data column or changing the data filtering method) generate a new report by repeating one of the processes listed with the report type.
Information Produced 
Report Types and How to Access Them 


Cross Validation Report  Data Statistics Report  Grid Contour Vol/Area Report  Gridding Report  Grid Information Report  Variogram Data Report 
Click Report in the Cross Validation dialog  Click the Statistics button in the Grid Data dialog  Click the Grids  Calculate  Contour Vol/Area command  Check the Grid Report Option on the Grid Data dialog  Click the Grids  Info  Grid Info command; or click Options  Grid Info in the Grid Editor  In the Variogram Properties click the Display Statistics button on the Statistics page and then click Report  
Data Counts, includes Filtered and at Validation Points 
X  X  X  X  
Filtering, includes Breakline, Duplicate, Exclusion 
X  X  
Grid Information, includes Grid Geometry 
X  X  
Gridding Rules 
X  X  
InterVariable Correlation, Rank Correlation and Covariance 
X  X  X  X  
Output Grid 
X  
Principal Component Analysis 

X 

X 


Polygon Used for Statistics 




X 

Regression, includes Planar: Z=AX+BY+C and Residual: R=AX+BY +C 
X 
X 



X 
Statistics, such as Univariate, Nearest Neighbor, and CrossValidation 
X 
X 

X 
X 
X 
Variogram Grid 





X 
Volume and Area 


X 



Z Transform, includes Grid and Data 



X 


Information Contained in Each Report Section
Each section of the report contains information about the grid, data, or variogram.
Time Stamp
Time of report 
Date and time the report was created in Mon Oct 14 10:43:13 2013 format 
Elapsed time to create grid 
Seconds required when gridding. Only included in the Gridding Report. 
Data Source
Source Data File Name 
path and file name of the data used in gridding 
X Column 
X data column 
Y Column 
Y data column 
Z Column 
Z data column 
Detrending 
variogram data detrending method selected on the General page in the New Variogram dialog. Only included in the Variogram Grid Report. 
Data Counts and Filtered Data Counts
Data Counts at Validation Points
The Data Counts at Validation Points section is only included in the Cross Validation Report.
Active Results 
locations at which the cross validation interpolation was successfully carried out 
NoData Results 
The NoData results are the locations at which cross validation interpolation was attempted, but was not successful. For example, the natural neighbor gridding algorithm can only interpolate at locations within the convex hull of the active data. As such, an observation that lies on the convex hull of the original, complete, data set will lie outside of the convex hull of the active data when that observation is the cross validation point. Cross validation is not possible using the natural neighbor algorithm at such a point, so it is assigned the NoData value. 
Attempted Results 
reports the number of locations at which cross validation interpolation was attempted 
Requested Results 
contains the original number of random data 
Z Data Transform
Includes the transformation method (if any) applied to the Z values. Lists the data that was unable to be transformed in a table.
The rest of the report information is calculated using the active data, including any artificial data generated by duplicate filtering. Excluded, deleted, or superseded data are not included in the following calculations.
Exclusion Filtering
Exclusion Filter String 
shows the Data Exclusion Filterstring 
Excluded Data 
number of data excluded by the Data Exclusion Filter  
Excluded Data Table 
the excluded data are listed in a table. The ID is equal to the line number in the original data file. This list is 100 data rows long by default. 
Duplicate Filtering
Duplicate Points to Keep 
To Keep filter used 
X Duplicate Tolerance 
maximum X spacing of points to be considered a duplicate 
Y Duplicate Tolerance 
maximum Y spacing of points to be considered a duplicate 
Deleted Duplicates 
number of duplicates deleted by the Duplicate Data filter  the deleted duplicates are listed in the Duplicate Filtering section 
Retained Duplicates 
number of duplicates retained by the Duplicate Data filter (this statistic is not computed if the duplicate rule is ALL)  the retained duplicates are listed in the Duplicate Filtering section including any artificial data 
Artificial Data 
number of artificial data created by the Sum, Average, and Midrange Duplicate Data filters 
Duplicate Data Table 
the duplicate data table lists all of the duplicate points with X, Y, Z, ID, and Status. The ID is equal to the line number in the original data file. When the status is artificial, no ID is given since this data does not come from the original data file. The Status (Retained, Deleted, or Artificial) reports how the duplicate was handled. This list is 100 data rows long by default. 
Breakline Filtering
When breaklines are used, data that is within the X Tolerance and Y Tolerance, as set in the Filter dialog, of the breakline are deleted due to breakline data superseding original data.
Anisotropy Angle 
the anisotropy angle reported for the default variogram 
Anisotropy Ratio 
the anisotropy ratio reported for the default variogram 
X Tolerance 
maximum X spacing of points to be considered a duplicate 
Y Tolerance 
maximum Y spacing of points to be considered a duplicate 
Superseded Data 
Superseded data are number of data eliminated by breaklines in the Data Statistics Report and the Gridding Report. Breakline data always supersede point data. If point data are on, or in the immediate vicinity of, breakline data the point data are eliminated. 
Breakline Data Table 
the breakline data table lists all of the superseded data points with X, Y, Z, ID, and Status. The ID is equal to the line number in the original data file. The Status (Retained, Deleted, or Artificial) reports how the duplicate was handled. This list is 100 data rows long by default. 
InterVariable Correlation
The InterVariable Correlation table shows the correlation between the X, Y, and Z variables. The Cross Validation Report also contains Estimated Z and Residual Z columns and rows. The correlations are computed with

The correlation is positive when both variables increase or decrease together. The correlation is negative when one variable increases while the other variable decreases. A correlation of zero shows that there is no linear relationship between the variables.
InterVariable Covariance
The InterVariance Covariance table shows the covariance between the X, Y, and Z variables. The covariances are computed with

The covariance is positive if, on average, the variables are both above the mean. The covariance is negative if one variable is above the mean and the other variable is below the mean.
InterVariable Rank Correlation
The InterVariance Rank Correlation table shows the rank correlation between the X, Y, and Z variables. The data is ordered and then assigned a rank value from 1 to the count of values. Rank values range from 1 to +1. The correlation is positive when both variables increase or decrease together. The correlation is negative when one variable increases while the other variable decreases. A correlation of zero shows that there is no linear relationship between the variables.
Univariate Statistics
This group of statistics shows information for X, Y, and Z data. These statistics do not include breakline data.
Planar Regression
Planar regression is an ordinary leastsquares fit where Z=AX+BY+C.

The Parameter Values are the A, B, and C values.

The Standard Error is the estimated standard deviation of the parameters.

The InterParameter Correlations are the correlation between A, B, and C coefficients.

The ANOVA Table shows regression statistics on the planar fit where df are the degrees of freedom and F is the ratio of the mean squares.

The Coefficient of Multiple Determination (R2) is calculated with

For the Cross Validation Report, the planar regression is the residual regression at the validation points.
Nearest Neighbor Statistics
The nearest neighbor statistics represent aspects of the data values and of the data locations. The nearest neighbor to a data point uses a simple separation distance without taking anisotropy into account. If two or more points tie as the nearest neighbor, the tied data points are sorted on X, then Y, then Z, and then ID. The smallest value is selected as the nearest neighbor.
The Separation column shows the separation distances between the observation and its nearest neighbor. The Delta Z column shows the absolute values of the differences between the observation Z value and the nearest neighbor Z value.
The statistics are the same as the Univariate Statistics (see above).
The Nearest Neighbor Statistics also includes the Complete Spatial Randomness section. The Complete Spatial Randomness statistics measure how random locations are in space. Surfer does not correct for edge effects so the statistics may be biased.
Lamda 
is the average spatial density

Clark and Evans 
where = average spatial density Si= separation distance between the observation and the nearest neighbor The distribution of this statistic is normal, with a mean equal to one and a variance of
See Clark and Evans (1954) and Cressie (1991) for more information. 
Skellam 
where = average spatial density Si= separation distance between the observation and the nearest neighbor The distribution is ChiSquared with 2N degrees of freedom. See Skellam (1952) and Cressie (1991) for more information. 
Principal Component Analysis
Principal component analysis (PCA) is a mathematical procedure that uses orthogonal transformation to convert a set of observations of possibly correlated variables into a set of values of linearly uncorrelated variables called principal components. The number of principal components is less than or equal to the number of original variables. The principal components are calculated for the X, Y, and Z values. A value is also reported for each principal component.
Variogram Grid
Max Lag Distance set on the General page in the New Variogram dialog 

number of Angular Divisions set on the General page in the New Variogram dialog 

number of Radial Divisions set on the General page in the New Variogram dialog 
Output Grid
Grid File Name 
name of the output grid file 
Grid Size 
number of rows and columns in the grid 
Total Nodes 
number of columns times the number of rows 
Filled Nodes 
number of grid nodes containing interpolated values 
NoData Nodes 
number of grid nodes containing the NoData value 
NoData Value 
reports the Z value associated with NoData nodes 
X Minimum 
minimum X grid line value specified in the Output Grid Geometry group in the Grid Data dialog 
X Maximum 
maximum X grid line value specified in the Output Grid Geometry group in the Grid Data dialog 
X Spacing 
X spacing set in the Grid Data dialog 
Y Minimum 
Minimum Y grid line value specified in the Output Grid Geometry group in the Grid Data dialog 
Y Maximum 
Maximum Y grid line value specified in the Output Grid Geometry group in the Grid Data dialog 
Y Spacing 
Y spacing set in the Grid Data dialog 
Grid Information
Grid File Name 
name of the output grid file 
Grid Size 
number of rows and columns in the grid 
Total Nodes 
number of columns times the number of rows 
Filled Nodes 
number of grid nodes containing interpolated values 
NoData Nodes 
number of grid nodes containing the NoData value 
NoData Value 
reports the Z value associated with NoData nodes 
Grid Geometry
X Minimum 
minimum X grid line value specified in the Output Grid Geometry group in the Grid Data dialog 
X Maximum 
maximum X grid line value specified in the Output Grid Geometry group in the Grid Data dialog 
X Spacing 
X spacing set in the Grid Data dialog 
Y Minimum 
Minimum Y grid line value specified in the Output Grid Geometry group in the Grid Data dialog 
Y Maximum 
Maximum Y grid line value specified in the Output Grid Geometry group in the Grid Data dialog 
Y Spacing 
Y spacing set in the Grid Data dialog 
Polygon used for statistics
Side 
Whether statistics were calculated for values Inside or Outside the polygon(s) 
Polygons 
Number of polygons used for calculating statistics 
Number of points 
Total number of vertices among the polygon(s) 
Gridding Rules
This section displays the gridding method used, as well as the option settings for each gridding method.
Univariate Grid Statistics
The Univariate Grid Statistics are the same as those reported in the Univariate Statistics and Nearest Neighbor Statistics sections.
Univariate CrossValidation Statistics
The Univariate Cross Validation Statistics section are the same as those reported in the Univariate Statistics. It also contains an additional column of data, called Data Used. This column shows the number of data points used in the calculation.
Volumes and Areas
Volume and area calculations are based on the Simple level method for contour line properties. Minimum and maximum contours along with the contour interval must be specified. Surface area and planar area calculations are made above, below, and between contours. Contour volume calculations are made above, below, and between contours.