With Void Analysis, you can analyze a prospective site's trade area (the analysis area) to identify gaps in specific businesses and services, compared to a similar reference area. For example, consider a scenario where a company is established in an area, and management is considering expanding into a different area that they consider to be a similar potential market. Specifying the current area as the reference area in Void Analysis, it can be compared against the analysis area, to help evaluate whether there is a gap in the type of businesses in which the company has a market presence.
The following step by step guide will provide a walkthrough of the Void Analysis workflow.
As a real estate developer, you want to identify whether there are gaps in Spring Valley, Nevada for certain categories of retail business and services, compared to the nearby town of Henderson, Nevada. Before starting Void Analysis, first use the Select Geography workflow to create two sites for Spring Valley, NV and Henderson, NV.
- Click Maps > Run Analysis > Void Analysis to launch the workflow.
The introduction screen provides an overview of the three phases in the workflow. To not see this screen again, select the Skip this in the future checkbox.
- Click Get Started.
The Void Analysis panel opens.
- Click Select Analysis Area.
The Select Analysis Area dialog opens. The analysis area is the area you want to analyze and identify whether any gaps are present. Since you just created the site for Spring Valley and had it open on the map, it is under the Currently on map tab. You would also find it under Recent tab. You can also browse all your sites under the From projects tab. Your can select multiple sites and neighboring geographies to make up your analysis area.
- Select the Spring Valley site and click Apply.
The specified Analysis area is now listed in the Void Analysis panel.You will set up the reference area, the area you want to compare with the analysis area, to determine the gaps.
There are two options to set up the reference area.
- Click Select Reference Area to select sites and neighboring geographies to make up the reference area.
- Click Increase analysis area to use as reference area to apply a buffer around the analysis area and use as your reference area.
- Using the first option, click Select Reference Area.
The Select Reference Area dialog opens.
- Select the Henderson City, NV site and click Apply.
The Analysis area and Reference area are now set up in the Void Analysis panel.
- Click Next.
In the resultant Void Analysis panel, business data will be used to determine the gap. To determine the gap, there are three ways to choose data for the void analysis.
- By category—you can select from Esri provided business data for analysis. Search by keyword to find matching businesses. You can click for Exact Match and Match Field options. To limit search results by category, expand the Category drop-down menu and select all the desired categories. Click More options to expand the view and select a different search type: Search by code (NAICS or SIC) or Show all businesses. Click Less options to collapse the view.
- Custom layer— you can use your own custom business data layer that you imported using the Web Maps and Layers or Import File workflows. The details for using Custom layer are described here.
- Use saved settings—open the Saved Settings dialog, move the pointer over a previously saved search and style settings, and click Use settings to apply and run the analysis.
- Click the By category tab, then click the Category drop-down menu.
You can select one or more categories.
- Click the Entertainment category and select Theaters - Movie. Click Food & Restaurants and select Bars and Coffee Shops.
In the above scenario, when multiple business categories or NAICS/SIC codes are selected, or if you choose to optionally group custom business data, the Void Analysis results will show the total gap or surplus for all businesses, as well as the gap or surplus for each category that you selected.
- Click Done.
The selected business categories are now listed in the Void Analysis panel. In the Field to determine void drop-down menu, you can select the field which will be used to compare the analysis and reference areas to determine the void or gap.
- Select Business Name, then click Run Analysis.The results are displayed under Summary in the Results panel and are also represented on the map.The results are calculated by subtracting the number of businesses in the Reference area from the number of businesses in the Target area. Each result indicates one of the following situations:
You can choose the default symbols that are shown on the map, under Preferences > Maps tab > Void Analysis.
- Gap—There are fewer businesses in the analysis area than in the reference area, indicated by symbol in the table. For example, in these results, there is a gap in number of Starbucks locations in the analysis area.
- Void—There are no businesses in the analysis area but some in the reference area, indicated by symbol. For example, in these results, there is a void of Village Pub and A Taste Of Coffee locations in the analysis area.
- Surplus—There are more businesses in the analysis area than in the reference area, indicated by symbol.
- Balanced—There are an equal number of businesses in the analysis area as in the reference area.
- Click the All drop-down menu to select an individual category and view the results for that category.
- To view the full table click View Full Table.
The Results table opens in Detailed view. By default, the table is sorted by Gap, from smallest to largest value. You can use the arrows next to the column headers to change the sorting order or variable. You can also click on any of the rows in the table to view the associated details. You can use the toggle in the top right to switch to Category view. In the Category view, you can see that the number of bars and coffee shops in the two areas are similar, but there is a significant gap in the number of movie theaters.
By default, values representing voids are indicated by rows colored red. You can click to open the Result Table Settings dialog, and enable colors for rows representing gaps, surplus and balanced values. You can click on the color thumbnails to modify the colors.
- Click to filter the results.
The Filter Results dialog opens.Select the Maximum results per category option and set an upper limit on the number results returned for any single category. If you want the table to only show the results that have a void, select the Show voids only check box. Select an attribute in the Filter layer by attributes drop-down menu and set filter settings to filter the business data layer by a desired attribute value.
You can set multiple attribute filters. Learn more.
Under Map Style, you can customize the appearance of the results on the map. By default, nearby point clusters are represented on the map by a single symbol. Uncheck the Cluster points check box to change the default. Expand Analysis area and Reference area to modify the fill and border type, color, transparency for the respective areas. You can set different symbols for different business categories on the map. Expand the All drop-down menu to select a category, select a symbol, and set the size and color.
- Click Save Settings to open the Save Settings dialog.
- Enter a name in the text box and click Save to save the current search criteria, map markers and area styling.
You can use these settings in a future analysis by selecting it from the Use saved settings dialog.
- To add a normalization variable, expand the drop-down list and select one of the listed variables, or click Browse for a variable to select another variable from the Data Browser.
Adding a normalization variable provides additional context to determine if a true gap exists or if it’s simply because the analysis area is smaller or has less people than the reference area. For example, the reference area may have more coffee shops, but also have a larger population to support them, whereas the analysis area could have fewer people and fewer coffee shops. To determine whether this is the case here, select Total Population as the normalization variable. The results in the table are updated. The Gap is -5, which means there are 5 fewer coffee shops in the Analysis area than in the Reference area, without accounting for any difference in population. Let us now examine the other values in the above table, to understand the gap normalized by total population.
The Reference Area Density is 10,137, which means that the reference area has 1 coffee shop per 10,137 population. You can move the pointer over the value in the table header to view a tooltip showing how the value is calculated.
The Analysis Area Density is 1 coffee shop per 8,321 people. Therefore, the analysis area has a higher density of coffee shops and a Difference in Density value of -1,816.
If we were to use the density of coffee shops in the reference area as our baseline and apply it to the analysis area, we would expect it to have just 21 coffee shops (the Expected in Analysis Area value). However, it has 26 coffee shops, which is 5 more, the Difference from Expected value. Since the Difference from Expected value is positive, it means that the analysis area has a surplus of coffee shops compared to the reference area, when normalized for the selected variable, Total Population. This is an example of a scenario where there is a gap when only the absolute difference in number of businesses is considered, but when normalized by the selected variable, it turns out to be a surplus, a more realistic analysis.
- Click Export to export the results.
The Export Results dialog opens. You can choose between the options to Export to Excel or Export to PDF. For both options, you can select the checkbox to Include individual business locations in the exported results.
Including individual business locations in the export uses credits.
Use a Custom layer
In Step 7 of the Void Analysis walkthrough above, the business data used to determine the gaps are chosen. You can select from the categories in the Esri provided business data within the application. Alternatively, you can choose a custom layer as the business data, by following these steps:
First, you will use the Web Maps and Layers workflow to add the following sample business data: https://services8.arcgis.com/cOQY5d2zYaXw1BYI/arcgis/rest/services/Void_analysis_sample/FeatureServer/
- Click Add Data > Web Maps and Layers and paste the above URL in the Search text box.
Click or press the Enter key. The sample data is added to your current project under the Web Maps and Layers section. To view the layer on the map, use the Zoom to web map option.The custom layer is now ready to be used in Void Analysis. Follow the steps in the above Void Analysis walkthrough, until you reach Step 7.
In the walkthrough above, Spring Valley and Henderson in Nevada are selected as the Target area and Reference area respectively. However, when using this custom layer, it is recommended to select the cities of Scottsdale and Mesa in Arizona as the Target area and Reference area.
- In the Choose business data to analyze step, use the Custom layer option to select the layer you previously added.Click Select Custom Layer.
The Add business layer dialog opens.
- Under the Web Maps and Layers section of the current project, select the layer you had added, and click Close.
The layer will now be selected as the business data to be used to determine the gaps in Void Analysis. The following drop-down menus are enabled:
- Field to determine void—the field in the layer used to determine whether the business has a gap or void. Select Business Name.
- (Optional) Choose field to group results—the field used to group the results into different categories, similar to categories selected under the By category option. For example, here Industry Description is selected, and the results will be grouped by the data layer's Industry Description field values: Pizza, Auto, Bank.
- Click Run Analysis.The results are displayed under Summary in the Results panel and are also represented on the map. For more information, see the step-by-step walkthrough in the previous section.
If the (Optional) Choose field to group results drop-down menu has no selection, the results will be shown as one category-in this case All.