Hot Spots Analysis

“Even random spatial patterns exhibit some degree of clustering. In addition, our eyes and brains naturally try to find patterns even when none exist. Consequently, it can be difficult to know if the patterns in your data are the result of real spatial processes at work or just the result of random chance. This is why researchers and analysts use statistical methods like Find Hot Spots (Getis-Ord Gi*) to quantify spatial patterns. When you do find statistically significant clustering in your data, you have valuable information. Knowing where and when clustering occurs can provide important clues about the processes promoting the patterns you're seeing. Knowing that residential burglaries, for example, are consistently higher in particular neighborhoods is vital information if you need to design effective prevention strategies, allocate scarce police resources, initiate neighborhood watch programs, authorize in-depth criminal investigations, or identify potential suspects.” - ArcGIS Website

Let’s try running the Hot Spots analysis on recent crime data (July 24 - August 4, 2016) from the city of Detroit, Michigan, in the table called “DPD_All_Crime_Incidents_July24-present_zip.xlsx.” You can obtain the data for yourself directly from the City of Detroit website. This table has been saved as an Excel workbook (.xlsx) rather than a CSV, the data converted to a table, and 2 crimes without location data have been removed. Additionally, the ZIP code associated with each location has been added to the table and a COUNT field has been added for a quick analysis.

Note: The file has 420 rows. Running the Hot Spots tool costs 1 credit per 1,000 features, so our tool will cost us 0.42 credits.

• 1. Use what you have learned to create a new map and add the crime data to the map. Use the CATEGORY column to categorize the symbol colors. Name the layer Crimes by category (color).

Can you identify any clusters in the distribution of crime incidents?

• 2. Click the Hot Spots Analysis tool on the ribbon.

• 3. Leave the default options, though set the resulting layer name as Crime Hot Spots. Check the box to save the results and click Run Analysis.

Are there any statistically significant clusters in the data?

How does this match your prediction?

• 4. Add the data to the map, but this time import them as polygons using the ZIP field and style using Counts and Amounts (Color). (When adding data From Excel, search the Location Type for Zip Codes and select the appropriate field).

• 5. Run the Hot Spots Analysis on the polygon data, using the Count field as the Attribute value in the analysis.

How does this compare to the previous results?

Enriching Your Data

“Mapping the data in your spreadsheet offers insight into spatial patterns and allows for quick and easy visual analysis, but there may be times where you want to quickly and easily add contextual information about the area surrounding that data. Esri's geoenrichment capabilities allow you to answer questions about locations that you can't answer with maps alone. For example: What kind of people live here? What do people like to do in this area? What are their habits and lifestyles? What kind of businesses are in this area?

Enriching your data allows you to add new columns of contextual data to the rows in your spreadsheet. You can choose from a number of demographic, business, landscape, and policy data collections. Each collection has multiple variables that can be added to your spreadsheet to help you better understand the area around your locations.” - ArcGIS Website

Using the Enriching Data service costs 10 credits per 1,000 features.

• 1. Select the Crimes by category (color) layer and click the Enrich Data button .

• 2. Browse the data and find one of interest to you. Click Next to until you reach the review screen.

• 3. Note the number of credits consumed by adding these data to your spreadsheet.

• 4. Click to add the data to your spreadsheet.

• 5. Add the new data to the map and look for new patterns!