Raster Overview Lab - Introduction to the Spatial Analyst
Introduction:
The Spatial Analyst can be used to decide where the optimum location for a business should be based on several parameters such as location of existing stores, location of competitors, spending habits of customers, location of customer, average traffic flow, land costs, zoning areas and planning rules.
In this assignment, you will examine existing coffee shops and their customers to find a good location for opening a new coffee shop.
In order to find a good location for a new shop, you will need to answer several questions: Is the new location too close to existing shops? Does the new location have similar characteristics to existing locations? Where are the competitors? Where are the customers? Where are the customers that are spending the most money at the store?
Exercise:
Download the data for the exercise here. Unzip the file.
Open ArcMap with an empty project. Add the layers coffee.shp, streets.shp and customers.shp. Turn of customers.
Make sure the Spatial Analyst Toolbar is available. For this choose Tools > Extensions and check the Spatial Analyst. Click close. Now open the Spatial Analyst Toolbar under View > Toolbars > Spatial Analyst.
Examine the locations of the existing shops (just the three ones in the middle are coffee shops). For this analysis, you will assume that any shops within 1 mile of each other will compete for customers. Potential sites for a new shop should therefore be more than 1 mile (5.280 feet) from any existing shops.
For this analysis you will follow the steps shown in the flow chart below.
You will start the analysis by creating a surface representing the distance from the shops. You will then create a surface representing the density of customer spending. Finally, you will query the distance and density layers to find the areas that are a mile or more from existing shops and with high spending density.
1. Creating the distance raster
From the Spatial Analyst menu, choose Spatial Analyst > Options. Click the Extent tab. Choose the Streets layer for the Analysis Extent.
In the Table of Contents, click the Coffee layer. From the Spatial Analyst menu, choose Spatial Analyst > Distance, then click Straight Line. The Straight Line dialog displays. For Distance to, make sure Coffee is selected. Click OK.
A distance surface is created and added to the map. Areas shown in yellow and orange are close to the shops, while areas shown in purple and blue are farther from the shops.
Move the Distance to Coffee layer to the bottom of the Table of Contents.
2. Creating the density raster
Next, you will examine the customer locations. This data base was created by address matching the stores data base of customer transactions over the last year with customer using an ID card for purchases.
A new shop will be more successful if there are lots of customers (who spend lots of money) near the location.
Turn off the Distance to Coffee layer and turn on the Customers layer. Right-click Customers and click Open Attribute Table.
Notice that the table has a SPENDING field, which indicates the amount of money customers spent over the last year. You will create a density surface of customer spending. Close the table.
In the Table of Contents, click the Customers layer. From the Spatial Analyst menu, choose Density.
The Density dialog displays.
For Input data, make sure that Customers is selected. For Population field, click SPENDING. Click OK.
A spending density surface is created and added to the map.
Change the name of the layer to Spending density. Move the Density from Customer Theme to the bottom of the Table of Contents. Turn off the Shops, Customers, and Streets layers so that you can see the density layer more clearly.
The dark blue areas have the greatest spending density of customers. Turn back on the shops. Are there shops located in each of the dark blue areas? There is a dense area that doesn't have a shop in the southwest part of town.
3. Determining the new location
You will finish the analysis by finding areas that are more than 1 mile (5,280 feet) from an existing shop and that are in a high spending density customer area.
From the Spatial Analyst menu, choose Raster Calculator. Create the following expression: ([Distance to Shops] > 5280) & ([Spending density] > .02). Click Evaluate.
A new layer is added to the Table of Contents. Change the name of the layer to Best locations.
Richt-click on the color field of the 0 in the new layer and choose no clor to make it hollow. Now the spending density is visible.
4. Choosing the location for the new Coffee shop and creating a layout.
You will now find the best area to locate a new coffee house based on areas greater than 1 mile from the existing store and in a high-density spending area.
The Best locations layer contains areas where you might focus efforts to find a new coffee shop location. Before selecting a final location, remember that there are many other factors to consider, including: the characteristics of existing shop neighborhoods, traffic counts, proximity to an interstate highway, income levels, population density, and age.
Now create a Layout of your choice and export it as Coffee.pdf. Submit it to your webfolder.
Lab updated by Eva Grund, May 2005.