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Jenness Enterprises

Mahalanobis Distances

The Mahalanobis Distances extension won 1st place in the Avenue category of the User Applications Software Fair; 2004 ESRI International User Conference, San Diego, CA, USA.

NAME:  Mahalanobis Distances   (Click Name to Download)

Adobe PDF Version of Manual:  Mahalanobis Manual (1.51 mb)

View and Download Mahalanobis Poster

Aka:  Mahalanobis.avx

Last modified:  December 9, 2003
     Manual modified May 4, 2004

TOPICS:  Mahalanobis, statistic, correlation, covariance, mean, matrix, distance, Pearson, Spearman, rho, landscape wildlife

AUTHOR:  Jeff Jenness
     Wildlife Biologist, GIS Analyst
     Jenness Enterprises
     3020 N. Schevene Blvd.
     Flagstaff, AZ 86004 USA

DESCRIPTION:  This extension produces several possible Mahalanobis-related outputs:

bulletThe View button  generates a Mahalanobis surface grid based on independent variable grids (see Mahalanobis Distance Grids).
bulletThe View button  recodes a Mahalanobis surface grid into a p-value grid based on a Chi-Square distribution with n-1 degrees of freedom, where n = # independent variable grids used to generate the Mahalanobis grid (see Mahalanobis Chi-Square Tools).
bulletThe View button  generates a Results table of Mahalanobis distances for each feature in a point, line or polygon theme (see Mahalanobis Theme Distances).
bulletThe View tool  allows you to click on a Mahalanobis surface grid cell and calculate the Chi-square p-value for that cell.  The p-values are reported in a text window (see Mahalanobis Chi-Square Tools).
bulletThe Table button  generates a new field in the current table containing Mahalanobis distances for each record in the table (see Mahalanobis Table Distances).
bulletThe Table button  generates tables containing mean vectors, covariance matrices, inverse covariance matrices, and correlation matrices for numeric fields in the current table (see Mahalanobis Statistical Matrices).

Please see Mahalanobis Description for a discussion of Mahalaobis distances in general.

REQUIRES:  ArcView 3.x and Spatial Analyst.  The extension will not load if Spatial Analyst is not present.

This extension also requires that the file "avdlog.dll" be present in the ArcView/BIN32 directory (or $AVBIN/avdlog.dll) and that the Dialog Designer extension be located in your ArcView/ext32 directory, which they usually are if you're running AV 3.1 or better.  The Dialog Designer doesn't have to be loaded; it just has to be available.  If you are running AV 3.0a, you can download the appropriate files for free from ESRI at:

Recommended Citation Format:  For those who wish to cite this extension, the author recommends something similar to:

Jenness, J. 2003.  Mahalanobis distances (mahalanobis.avx) extension for ArcView 3.x,  Jenness Enterprises.  Available at:

Please let me know if you cite this extension in a publication (  I will update the citation list to include any publications that I am told about.

Using the Mahalanobis Distances Extension:

  1. Begin by placing the " mahalanobis.avx" file into the ArcView extensions directory (../../Av_gis30/Arcview/ext32/).
  2. After starting ArcView, load the extension by clicking on File --> Extensions… , scrolling down through the list of available extensions, and then clicking the checkbox next to "Mahalanobis Distances."

Each Mahalanobis operation is described in detail in the following pages:

Mahalanobis Description  |  Generating Mahalanobis Grids  |  Mahalanobis Chi-Square Tools  |  Mahalanobis Distances for Feature Themes  |  Mahalanobis Distances for Tables  |  Additional Mahalanobis Matrices  |  Mahalanobis References

Download Extension  |  Download Manual

Enjoy! Please contact the author if you have problems or find bugs.

            Jeff Jenness                            

            3020 N. Schevene Blvd.

            Flagstaff, AZ  86004


Please visit Jenness Enterprises ArcView Extensions site for more ArcView Extensions and other software by the author.  We also offer customized ArcView-based GIS consultation services to help you meet your specific data analysis and application development needs.