Point features in an overlapping buffer area are calculated twice, creating a false result of the overall point count within the region.
The image below shows the distribution of crime occurrences and police stations in Lincoln, Nebraska. The total number of crime incidents within 0.5 miles radius of police stations is determined by creating an overlap buffer of 0.5 miles radius from each police station.
Running the Summarize Within analysis on the overlapping buffer area, and the Statistics command from the attribute table on the recently created Summarize Within layer, calculates the total number of point features to be 395.
This problem occurs because the default overlap buffer is used instead of the dissolve buffer. The overlap buffer keeps the common area, and so calculates the point features in the overlapping area twice. In contrast, the dissolve buffer combines the common area into a single feature, and so calculates the point features in the overlapping area once.
There are two ways to ensure the point features in the overlapping buffer area are only calculated once, that is, using the Dissolve buffer type or using the Dissolve Boundaries tool.
Note: The Create Buffers and Dissolve Boundaries analyses use 1 credit per 1000 features for each analysis. For more information on credit usage, refer to ArcGIS Online Help: Understand credits.
This option is suitable for a project with existing overlapping buffers.
Note: To create a single restricted buffer zone for buffer zones from multiple layers (for example, combining police station, library, and school buffers), navigate to Analysis > Manage Data > Overlay Layers. In the Choose overlay method step, select the Union option. Proceed with the Dissolve Boundaries analysis to create a single buffer zone. For more information, refer to Analytics: Are liquor stores too close to schools, libraries, and parks?
Get help from ArcGIS experts
Download the Esri Support App