Working with Data and Reports

Choosing Reports and Maps

With ArcGIS Business Analyst and Business Analyst Online, you can generate reports that help you analyze and understand your market and your customers in a variety of ways. Whether you want to evaluate potential sites, profile your customers, or scan new markets, Business Analyst products offer a number of reports and analyses that provide you with information to help you in your decision-making process.

Find out which reports can help you to

• Evaluate Sites
• Scan New Markets
• Determine Market Penetration
• Reach Your Customers More Effectively
• Develop, Plan, and Analyze Franchise Territories

Below are some key concepts and definitions to help you understand how parameters are set up and what they encompass when choosing/generating reports and conducting various analyses.

Defining a Study Area

There are two types of study areas: geometric and geographic. Rings (or radii), donut rings, drive-time polygons, and hand drawn shapes are geometric study areas. Geographic study areas are based on standard geographic units such as the entire United States, a single state, Core Based Statistical Area (CBSA), Designated Market Area (DMA), congressional district, county, county subdivision, place, ZIP Code, or census tract. You can use any combination of these study area types to provide a side-by-side comparison of a specific site to the region in which it is located. Learn more about how data is calculated for a study area.

Reports Based on Geometric Study Areas

• Rings or radii. Ring reports have been the traditional choice for analyzing demographic data. Choose an intersection or address or a predetermined latitude and longitude as the centerpoint. A one-, three-, or five-mile ring report describes the data in the study area.
• Donut rings. Reports based on donut rings, or bands, are similar to ring-based study areas without the overlap. Choose an intersection, address, or predetermined latitude or longitude as the centerpoint. A one-, three-, or five-mile ring report describes the data in the study area.
• Drive-time polygons. These are defined by the time it takes to drive from the outer border of an area to a site location. Drive-time polygons are suitable for defining areas where access to a site is greatly affected by natural or man-made barriers, such as mountains, rivers, bridges or highways, and take into consideration the total drive time under normal traffic conditions. Choose an intersection, address, or predetermined latitude or longitude as the center point. A 5-, 10-, or 15-minute drive-time report describes the data in the study area. You can choose up to 60 minutes of drive time to the specified location.
• Hand drawn shapes. Draw your own shapes to define a unique study area such as sales territories or distribution regions.

Reports Based on Geographic Study Areas

• United States. An area aggregating the 50 United States and District of Columbia.
• Single state. The primary political and administrative subdivision of the United States. The District of Columbia is included as a state-equivalent area.
• Core Based Statistical Area. Represents both revised Metropolitan Statistical Areas and the new Micropolitan Statistical Area.
  
  New metropolitan and micropolitan statistical area definitions were announced by the U.S. Office of Management and Budget in June 2003, based on application of 2000 standards with Census 2000 data. Metropolitan and Micropolitan Statistical Areas are collectively referred to as CBSAs.
  
  Metropolitan Statistical Areas have at least one urbanized area with a population of 50,000 or more, plus adjacent territory that has a high degree of social and economic integration with the core area as measured by commuting times.
  
  Micropolitan Statistical Areas are a new set of statistical areas that have at least one urban cluster with a population of at least 10,000 but less than 50,000. It also includes adjacent territory that has a high degree of social and economic integration with the core area as measured by commuting times.
  
  Metropolitan and Micropolitan Statistical Areas are defined in terms of whole counties or county equivalents (e.g., the six New England states).
  
  More information can be found at www.census.gov/ population/www/estimates/aboutmetro.html.
• Designated Market Area. A television market as defined by Nielsen Media Research.
• Congressional District. One of the 435 areas from which people are elected to the U.S. House of Representatives. Congressional seats are apportioned among the states after each decennial census, based on population counts. Each state is responsible for establishing districts that are as equal in population as practicable for the purpose of electing representatives.
• County. The primary political and administrative subdivision of a state.
• County Subdivision. The primary division of counties and county equivalents for the reporting of decennial census data. County subdivisions include census county division, census subareas, minor civil divisions, and unorganized territories.
• Place. An incorporated community or a location designated by a state or local government for communities that are not legally incorporated.
• ZIP Code. An area created by the U.S. Postal Service to facilitate mail delivery.
• Census Tract. A small statistical subdivision of a county. Local committees usually delineate tracts to represent relatively homogeneous neighborhoods of approximately 1,500 to 8,000 residents.

How is data calculated for a ring?

ESRI uses a sophisticated Weighted Block Centroid geographic retrieval methodology to calculate data for rings and other centroids. This method provides the most accurate information for rings and polygons.

The Basic Principle

A geographic retrieval methodology determines how data is gathered and then summarized or aggregated for each ring. For standard geographic units, such as counties or ZIP Codes, the link between a designated area—called a trade area—and its attribute data is a simple one-to-one relationship; if a trade area contains a selection of ZIP Codes, the data retrieval is a simple process of gathering the data for those ZIP Codes.

The geographic retrieval process for rings is more complicated because a ring may transect a geographic unit such as a county or ZIP Code. How much of a geographic unit must fall inside the ring for it to be included in the data? Can the aggregation include only data for that portion of the geographic unit that falls inside the ring? There are two approaches to solving this dilemma—Simple Block Group retrieval and Weighted Block Centroid retrieval.

Simple Block Group Retrieval

To produce a report of data for these areas, underlying geographic areas must be collected. The most basic method for aggregating data for trade areas is to use a point-in-polygon approach to gather the census block groups within the trade area and aggregate the data for the block groups.

The map to the right illustrates a store location within a ring with a one-mile radius. The highlighted polygons within the ring represent all the block groups within the trade area selected by the point-in-polygon procedure. By using a Simple Block Group Retrieval methodology, the population of each selected block group would be aggregated to create a trade area total.

Why Simple Block Group Retrieval Is Inaccurate

The map on the right shows a more detailed view of two specific block groups from the map shown above. The block group highlighted in yellow (340030473003) illustrates the fundamental weakness of using block groups exclusively in a point-in-polygon approach. Because the centroid of the polygon is within the one-mile radius, the entire block group is included in the aggregation. For example, if a user calculates population for the one-mile radius trade area, the entire population of the highlighted polygon is included in the total even though approximately half of the block group is outside the trade area. This assignment weakness can severely skew the results of a trade area aggregation because many block groups contain a large population.

The inverse of this apportionment problem also contributes to the inaccuracy of this geographic retrieval approach. In the same example, the map above shows a portion of block group 340030614001 within the trade area ring. However, none of the block group's attributes will be utilized during the aggregation process. This can have a significant effect on the aggregation process and contributes to inaccurate information on demographic reports.

Why Weighted Block Centroid Retrieval Is Better

ESRI employs more sophisticated geographic retrieval methodology to aggregate data for rings and other polygons. The Weighted Block Centroid retrieval approach uses census block data to better apportion block groups that are not exclusively contained within a ring.

Census blocks are the smallest unit of census geography. They are used to create all other levels of census geography. For example, one or many blocks are aggregated to create a block group. In the map to the right, the blue dots represent the geographic centroids for the 13 blocks that make up the yellow highlighted block group. Only a small subset of data (households, population, housing units, and number of businesses) is available at the census block level and, therefore, cannot be used to aggregate most data for a ring.

Using block centroids within a trade area to calculate a weight for a block group allows you to use the Weighted Block Group to more accurately gather and aggregate demographic data for rings and other polygons.