Jenks Natural Breaks Classification

From Wiki.GIS.com

The Jenks Natural Breaks Classification (or Optimization) system is a data classification method designed to optimize the arrangement of a set of values into "natural" classes. This is done by seeking to minimize the average deviation from the class mean, while maximizing the deviation from the means of the other groups. The method reduces the variance within classes and maximizes the variance between classes.^[1][2]

The Jenks scheme determines the best arrangement of values into classes by iteratively comparing sums of the squared difference between observed values within each class and class means. The best classification identifies breaks in the ordered distribution of values that minimizes within-class sum of squared differences.

[edit] Using Jenks Classification in GIS

Cartographers and map makers can utilize the Jenks method to identify break points in a data set by picking the class breaks that best group similar values and maximize the differences between classes. The features are divided into classes whose boundaries are set where there are relatively big jumps in the data values.

In the legend of the example map, note the variance in the range of percentage values of groups in the map. The Jenks Natural Breaks in the data are utilized to provide more meaningful visualization of map data based on the "natural breaks' in the data identified by the iterative process. Other methods of data classification used in GIS include Natural Breaks (without Jenks Optimization), Equal, Defined, or Geometric Interval, Quantile, and Standard Deviation.

[edit] References

• ESRI FAQ, What is the Jenks Optimization method
• Terraseer

[edit] Sources

ESRI ArcGIS Resource Center - Classifying numerical fields for graduated symbols