Introducing GeoDa 1.8
GeoDa is a free and open source software tool that serves as an introduction to spatial data analysis. It is designed to facilitate new insights from data analysis by exploring and modeling spatial patterns.
GeoDa was developed by Dr. Luc Anselin and his team. The program provides a user-friendly and graphical interface to methods of exploratory spatial data analysis (ESDA), such as spatial autocorrelation statistics, and basic spatial regression analysis for lattice data (points and polygons).
Since its initial release in February 2003, GeoDa's user numbers have increased exponentially to over 160,000 (June 2016). This includes lab users at universities such as Harvard, MIT, and Cornell. The user community and press embraced the program enthusiastically, calling it a "hugely important analytic tool," a "very fine piece of software," and an "exciting development."
The latest version 1.8 contains several new features such as support for more spatial file formats, full space-time data support in all views, basemap layers for all maps, averages charts, scatter plot matrices, nonparametric spatial autocorrelation (correlogram), and flexible data categorization.
A new workbook is under development. In the meantime, here are interim resources, including an overview of features in 1.8+.
A New Look
After years of using the same old icons, GeoDa now has a new look:
GeoDa runs on Windows, MacOSX and Linux (Ubuntu)
GeoDa Now Supports More Spatial Data Formats
GeoDa now supports a larger variety of vector data in different formats (click here to see the details): You can work with shapefiles, geodatabases, GeoJSON, MapInfo, GML, KML, and other vector data formats supported by the GDAL library. The program also converts coordinates in table format (.csv, .dbf, .xls, .ods) to one of these spatial data formats and converts data between different file formats (such as .csv to .dbf or shapefile to GeoJSON). Selecting a subset and exporting it as a new file is now also possible.
Connect to CartoDB from Within GeoDa
You can now load data from CartoDB into GeoDa and save results back to the CartoDB table. See how this works.
Explore Statistical Results through Linked Maps and Charts
In contrast to programs that visualize raw data in maps, GeoDa focuses on exploring the results of statistical tests and models through linked maps and charts.
Analyze Spatial and Temporal Patterns Across Linked Views
You can now group the same variable across time periods in the new Time Editor to explore statistical patterns across space and time. Then explore results as views change over time with the Time Player.
Ground-Truth Map Results with Basemaps
If your spatial data are projected (.prj file), you can now add a basemap to any map view, including cluster maps, for better orientation and for ground-truthing results.
Compare Averages Across Time and Space
A new Averages Chart compares values that are averaged over time and/or space and tests if the differences in these means are significant. For instance, first select if you want to compare means of selected vs. unselected observations in the same time period or compare all observations for different time periods. A basic pre-post/impact-control test then indicates if your results changed over time and space (using an F-test and difference-in-difference test).
Detect Relationships in Multivariate Space
A scatter plot matrix allows you to explore multiple bivariate correlations at once. In this example, the regression slopes for selected, unselected and all police precincts in San Francisco are shown to explore relationships between four types of crime.
Determine if Changes Over Time Are Spatially Clustered
Use a global or local Differential Moran's I test to find out if a variable's change over time in a given location is statistically related to that of its neighbors. For instance, this local (LISA) cluster map shows hotspots in New York with larger changes in the share of kids between 2002 and 2008 (and coldspots with smaller changes).
Find the Threshold Where Spatial Correlation Ends
A nonparametric spatial autocorrelation test (correlogram) is now available to determine distance thresholds when the values of neighboring pairs are no longer correlated.
Explore the Impact of Flexible Data Categorization
With the new category editor, you can explore how sensitive your results are to changes in the thresholds that categorize your data. In this example the thresholds in the conditional map (right) are based on the categories that can be adjusted in the category editor (left).
GeoDa is released under a GPL license. It builds on several open source libraries and source-code files. Below is the list of the key projects that we would like to acknowledge.
GDAL Libraries, version 1.10 License: X/MIT style Open Source license Authors: many Links: http://www.gdal.org/
Boost Libraries, version 1.53 License: Boost Software License - Version 1.0 Authors: many Links: http://www.boost.org/ http://www.boost.org/LICENSE_1_0.txt
Boost.Polygon Voronoi Library, Boost version 1.53 License: Boost Software License - Version 1.0 Author: Andrii Sydorchuk Links: http://www.boost.org/ http://www.boost.org/LICENSE_1_0.txt
wxWidgets Cross-Platform GUI Library, version 2.9.4 License: The wxWindows Library Licence Authors: Julian Smart, Robert Roebling, and others Links: http://www.wxwidgets.org/ http://www.opensource.org/licenses/wxwindows.php
CLAPACK Linear Algebra Libraries, version 3.2.1 Authors: many License: Custom by University of Tennessee Links: http://www.netlib.org/clapack/ http://www.netlib.org/lapack/lapack-3.2/LICENSE
Approximate Nearest Neighbor Library, version 0.1 Note: Full source of 0.1 release included in kNN directory Authors: Sunil Arya and David Mount License: See kNN/AHH.h in included source files Links: http://www.cs.umd.edu/~mount/ANN/
FastArea.c++ source code Note: We have based the source for functions findArea and ComputeArea2D in our file GenGeomAlgs.h from FastArea.c++ in Journal of Graphics Tools, 7(2):9-13, 2002 Author: Daniel Sunday License: unknown Links: http://jgt.akpeters.com/papers/Sunday02/FastArea.html
logger.h source code Author: Seweryn Habdank-Wojewodzki Note: We have copied the source for logger.h and modified it slightly to work with wxString. License: Boost Software License - Version 1.0 Links: http://accu.org/index.php/journals/1304
nullstream.h source code Author: Maciej Sobczak License: See logger.h in included source files Links: http://www.msobczak.com/
The development of GeoDa has most recently been supported by the National Science Foundation, the National Institutes of Health, the National Institute of Justice, and the Agency for Healthcare Research and Quality.
We are currently updating the documentation to reflect the new features in GeoDa 1.8. The Openspace listserv supports technical questions about GeoDa.
GeoDa uses a GPL License (General Public License).
Questions? Contact us.