"Turning the [Attribute] Tables to
The following text is Gil Castle's final draft of the real estate column appearing in Business Geographics, August 1995
Copyright © 1995 GIS World, Inc.
My previous two real estate columns on information sources addressed in-house, proprietary data bases ("The Family Jewels," BG January 1995) and digital files ("Let's Make a Map," BG April 1995). The focus of this column is on tabular files-also called attribute data-acquired from private sector vendors and public sector agencies. In real estate, as in most other industries, a useful way to categorize attribute data is by demand and supply.
A common example of demand-side attribute data is demographic information displayed at the census tract level. In a GIS, a map of census tracts for a metropolitan area, submarket, or other study area is linked to a tabular file. The rows of the table correspond one-to-one to the map's census tract; the columns contain the variables of interest to the user. Demand-side information typically used in real estate are historic, current, and forecast figures on population, households, income, age distribution, employment, retail purchases, etc.
Many sources of demand-side data exist, including the original source for most of the information-the U.S. Bureau of the Census (301-457-4100). Vendors with significant market share include, in alphabetic order: CACI Marketing Systems (800-292-2224), Claritas (703-812-2836), Conquest (408-970-9600), Equifax/National Decision Systems (619-622-0800), Market Statistics (212-592-6259), and Urban Decision Systems (800-633-9568). Information on the considerable array of other private and public sector sources is available in two GIS World, Inc. publications: Profiting from a Geographic Information System, and The International GIS Sourcebook.
The good news: the number and diversity of demand-side data vendors are extensive, and hence the prices are highly competitive; the leading GIS software vendors are resellers of many of the data bases via their data catalogs, to facilitate "plug-and-play;" and most data vendors are compatible with most GIS software, so users do not have to be locked into whatever source a given GIS software vendor promotes the most. The bad news: one can spend a considerable amount of time exploring the differences between the alternative sources when trying to decide which to buy.
An example of a supply-side attribute data is a table in which the rows correspond to the submarkets for a given property type in a given metropolitan area, and the columns contain the total inventory (number of of buildings and aggregate square footage), new construction, demolitions, and net absorption. Another example is a table in which the rows correspond to individual properties and the columns provide both physical characteristics (e.g., property type, class, when built, number of stories, parking spaces) and financial information (e.g., asking rents, vacancy rates, operating expenses, net operating income, last selling price and selling date).
Reliable sources of supply-side data are far fewer than the demand-side. One reason is that the federal government does not collect this information every ten years. A second and more important reason is that real estate companies do not have an incentive to share their data, because real estate is essentially a game of information arbitrage. Supply-side data thus tends to be more valuable than demand-side data.
A few companies provide submarket and/or property-specific information in GIS format throughout the nation. For example, the longitude-latitude coordinates and various attribute data are available (via the data catalogs of major GIS vendors or directly from the original sources) for 32,000 shopping centers; 29,900 supermarkets and grocery stories; 15,300 chain drug stores; 14,900 mass merchandisers; 90,000 financial institutions; 370,000 restaurants, and so on. REIS Reports (212-481-8500) monitors and forecasts rents, vacancy rates, and other pro forma information for approximately 100,000 office, retail, warehouse and apartment properties in the top 50 Metropolitan Statistical Areas (MSAs); REIS Reports compiles the information by periodically calling individual building owners and managers.
Other national vendors compile their data bases by assembling, verifying, augmenting and repackaging the information from county assessors, city recorders, and other local government agencies. The leaders cover approximately 100 to 400 counties on the West Coast, in Florida, and a few other key states, with more counties being added each month. The major players include Metroscan (800-879-9223), TRW REDI Property Data (800-426-1466), and DataQuick (619-455-6900). These sources are GIS-compatible to varying degrees; that is, some will sell any portion of their data bases with each property's longitude-latitude coordinate, while others will provide the geocodes only for major data purchases.
While national vendors are few, most cities have a local company that compiles and resells government data. Many of these local companies are just beginning to experiment with making their data available in geocoded form, and undoubtedly others with soon follow. To date the use of GIS by these local vendors has been limited, such as simply displaying the locations of properties fulfilling a customer's selection criteria. In this regard the vendors are viewing GIS in a manner similar to the ever increasing number of multiple listing services that are adopting the technology (see "Digital home buying services available" in BG March 1995).
Vendors of both demand-side and supply-side data realize that the $10 Trillion real estate industry is becoming ever more data-intensive. Whoever captures and retains a major market share of the data sales nationwide will enjoy huge revenues. Innumerable players, large and small, are now scrambling to be distributors of geocoded data by disk, CD ROM, and modem-to the benefit of us all.