Feature Story

Authority and Authoritative Data: A Clarification of Terms and Concepts by David Stage

The statements made or opinions expressed by authors in Fair & Equitable do not necessarily represent a policy position of the International Association of Assessing Officers.

his article is intended to clarify the issues surrounding it is fairly easy to give the data the benefit of the doubt as long the terms authority and authoritative as they relate to as there are no glaring errors. On the other hand, if the users Tsources of parcel data and the sharing of those data. are Small Business Administration managers providing disaster Claims are frequently made, implied, or omitted about the ap- victims with low interest loans, then they want the data to be propriateness of applications and data sources that purportedly of the highest quality to ensure these loans are being awarded represent the extent of rights in land, the characterization of to the owners of the property and the value of that property those lands, and the status of ownership. These claims have is what the applicant claims it to be. caused a great deal of confusion for the public as well as for professionals in two ways: first in how the source is chosen and Data Quality the data are used and second in the discourse among cadas- What is data quality? One definition states that, “data are of tral data stakeholders. These issues are interrelated with the high quality if they correctly represent the real-world construct terminology used to describe the production and publication to which they refer.” A more technical definition declares of cadastral data, but that terminology is treated only briefly quality to be “the state of completeness, validity, consistency, here, since it should be the subject for another article. timeliness and accuracy that makes the data appropriate for a specific use” (Wikipedia contributors 2009). Determining an appropriate level of quality requires the user to first define With few exceptions, assessment data their real-world construct, otherwise known as business require- are developed under the auspices of an ments, and then match those requirements with the source data to determine whether the quality (completeness, validity, assessor’s office. consistency, timeliness, and accuracy) of the data meets their specifications. This process leads to determining the best source for the needed data. The proliferation of parcel data sets on the Internet is push- ing this issue into the public arena, but not because the data Data Sources What are the different data sources of assessment data for looks bad. As a matter of fact, the data that are available look a user? With few exceptions, assessment data are developed quite good and seem to work well in the applications in which under the auspices of an assessor’s office. These data can be they are being used. In these images, property boundaries and acquired and packaged in a variety of ways. It is important to those in the neighborhood appear to be exactly where they characterize and understand the subtle differences in the fol- are supposed to be and the value does appear to be accurate, lowing terms when data sources are being considered. so why can’t these data be used to address all land ownership needs? Answering this question requires an understanding of • Authoritative Data. These are officially recognized data that a number of issues, ranging from technical and legal to busi- can be certified and provided by an authoritative source. ness processes and semantics. • Authoritative Data Source (ADS). This is not a source of In making assumptions about data, users should recognize data, but it is mistakenly used as one when data sources are the inverse relationship between the distance of the leap-in- discussed. ADS is an information technology (IT) term sys- faith needed to use the data and the likelihood the user will be tem designers use to identify a system process that ensures disappointed, publicly embarrassed, or even worse. The first the veracity of data sources when a database is created. question users should ask is whether they can trust the data. • Authoritative Source. This is an entity authorized by a legal Are the data sufficiently accurate to answer the questions the authority to develop or manage data for a specific business user wants answered? If the user is simply satisfying curiosity, purpose. The data this entity creates are authoritative data.

Fair & Equitable • February 2009 13 • Authority. In the context of public tative sources. These publications are issues are particularly problematic for agencies, authority is the legal respon- often compilations and subsets of the copies of the original source data, which sibility provided by a legislative body to data from more than one authoritative are also known as shadow data. conduct business for the public good. source. These data are trusted because In summary the term ADS, even • Authorization. This is the result of an there is an official process for compil- though it is a best practice of the IT act by a legislative or executive body that ing the data from authoritative sources community, implies more than it able to declares or identifies an agency or or- and the limitations, currency, and at- deliver. ADS is an IT term that describes ganization as an authoritative source. tributes are known and documented. an IT process in an information storage The term ADS deserves to be elaborat- • Certified Data. These data are created system (data warehousing) that ensures ed upon for two reasons, first the term is for a specific purpose and have been the integrity and validity of the data being often confused with authoritative data and vetted by an authorized entity. stored, but it does not necessarily mean authoritative source and second because that it is authoritative data coming from • Uncertified Data. Uncertified data are ADS methodology, which is a best prac- an authoritative source. (IT terms are generally a more current copy of the tice of the data warehousing community, labels used in computer-world constructs, data that has yet to be certified and should be kept in mind when comparing not real-world constructs. IT terms often may also include information used for authoritative data and shadow data. suggest similar real-world functionality creating certified data but is not part From a technology perspective, in- but are metaphors at best. These terms of the certified data. formation managers create processes should be qualified with the prefix “e-” for in which an information storage system electronic. Consider the terms desktop, win- The sentence “The is the authoritative data source and is de- dow, and trash. Their meaning would be fined for each data element or piece of more clear if they were e-desktop, e-window, integrity and validity of information. These systems can be quite and e-trash. One term that did manage to hang on to its prefix is .) any data set is open to complicated, because data sets are being e-mail built by outputting data from multiple question when there is sources and then re-presenting the Real-World Operations results for new business purposes. The The primary use of assessment data is the no traceable connection problems faced in compiling data from valuation of property for tax purposes. multiple systems are as follows: The state legislature usually provides with a known System assessors with this authority alone. The of Record” deserves In these cases, multiple information expenses incurred in collecting data are systems (multiple jurisdictions) may justifiable only if they enhance the qual- repeating. disagree about the same piece of informa- ity of the information used to assess prop- tion. These disagreements may stem from erties and conduct the businesses of the semantic differences; differences in the assessor’s office. It is not a mandate of the • Data Steward. This is the organization timing of the extraction, transformation assessor’s office to provide high-quality within an authoritative source charged and loading (ETL) extracts that create data for other business processes. the data they report against; or may sim- with the collection and maintenance Nevertheless, the utility of assessment ply be the result of bugs. of authoritative data. The term data data is of great value to many organiza- steward is often confused with the term Where the integrity of the data is vital, a tions. These data provide the greatest authoritative source. data element must either be linked to, or degree of granularity for describing the • Shadow Data. These are copies of the extracted directly from its system of record. characteristics of property and, with assessor’s data that are packaged and The integrity and validity of any data set is the advent of geographic information often enhanced or value-added for open to question when there is no traceable systems (GIS), a good visual description distribution and resale. The enhance- connection with a known System of Record. of the parcel boundary. The data in ments may consist of reorganizing the (Wikipedia contributors 2009) most jurisdictions are continually being structure of the data, putting the data The sentence “The integrity and validity updated, so they accurately portray the in a reseller’s format, and/or adding of any data set is open to question when current status of all properties. The data data from sources to make a new data there is no traceable connection with a are often validated by two sources: the set. The level of trust that can be placed known System of Record” deserves re- assessment office through its own quality in the data depends upon how much peating. This statement is true, but there control and a state oversight agency. the user knows about the data and the are also degrees of integrity and validity, In short, the product is of a very high degree to which the enhancements im- for example, the degree to which the quality for its intended purpose, and a prove the data or “muddy the waters.” completeness and accuracy of the data subset of information coincides with the • Trusted Source and Trusted Data. This have degraded since the last update, or business needs of organizations for an is a service provider or agency that pub- the degree to which the “waters are mud- accurate portrayal of how the land is be- lishes data from a number of authori- died” by normalization of the data. These ing used, who is using it, and what is on

14 Fair & Equitable • February 2009 Feature Story the land. The information requirements Figure 1 is an illustration of this model known accuracy and lineage and can be of these organizations can be described showing the relationship between the data verified and certified by data stewards in as highly coincident, and many organi- sources, their legal authority for creating the authoritative source. zations are looking for ways to acquire the data, and the different types of data— regular access to these data. production, publication, and project. Trusted Data and Trusted Data Sources Trusted data and trusted data sources describe The following describes the compo- a situation in which data sets are published The primary use of nents of the data-sharing model. by someone other than the authoritative assessment data is the Application service providers require source and are often the compilation of official sources of data if their applica- multiple sources of authoritative data. The valuation of property for tions are to be credible. Thus the source data are trusted because there is an official is authorized by a public body such as a process for compiling the data from au- tax purposes.… It is not a federal agency, state legislature, or local thoritative sources and the limitations, cur- mandate of the assessor’s government statute or rule. The two rency, and attributes are known. Metadata types of official data areauthoritative and are provided; the data are often formatted office to provide high- trusted data, and correspondingly there into a standardized form; and linkages to are authoritative and trusted sources for the originating source are provided with quality data for other these two types of data. the data. This trusted source is recognized by the authoritative source as an official business processes. Authoritative Data publisher of this subset. Typically a trusted Authoritative data come directly from the source is established to integrate data from creator or authoritative source. These multiple jurisdictions and to compile them Government-to-Government data are the most current and accurate into a standard format. These trusted Data Sharing and have been vetted according to of- data are adequate, convenient, and cost- Government agencies need high-quality ficial rules and policy. The data have a effective for users that need a regional view data because they are making decisions that often affect life, property, and the Figure 1. Illustration of the relationships among the defined terms. economic viability of communities. Given the option, government agencies would Publication Data prefer to go to the assessor’s office to acquire high-quality authoritative data to base their decisions on. The issues of User Access sharing data and providing benefits di- rectly to the assessor’s office, as opposed to benefits to the community as a whole, Trusted Source are complex and should be the subject Publish and Provide Access Trusted of another article. Has agreement/understanding Data* The purpose here is to describe a with Authoritative Source process, define the components of a Provides standardized data Provides Metadata data-sharing model, and differentiate authoritative data from shadow data. The following is the vision of the Federal Geo- Annual Updates graphic Data Committee for the National Spatial Data Infrastructure (NSDI) and the National Cadastre within the NSDI. Authoritative Project Data The Cadastral NDSI will have a single Source Authoritative source of authoritative cadastral data Data Steward Data* within a single geographic extent that is controlled and managed by designated Production Data data stewards. Access to this data is fa- cilitated by compiling and integrating the data into trusted data sources at state or re- Authorization/Official gional levels. This will reduce duplication Recognition of Authority of effort and assure that the best available information is used in decision making. Legislation/Executive Order/Ordinance (FGDC Accessed 1-19-2009)

Fair & Equitable • February 2009 15 and have to deal with multiple sources of Metadata is essential to (1) protecting individual data. However, there is an understanding Metadata are an essential part of the land rights, (2) supporting local govern- of the necessity when final decisions are process; they allow the user to determine ments and other parcel producers in being made, particularly about rights the usability of the data as well as serve their authorized role of data stewards, and interests of specific properties, that as an audit trail on the authority of the and (3) ensuring that the user com- users must go to an authoritative source data. Trusted data sources and authorita- munity has the best available and most and acquire authoritative data directly to tive data sources must provide accurate current cadastral information. ensure that they have the most current metadata that describe the lineage, qual- and accurate data. ity, and currency for cadastral data. In References addition, the trusted data sources must Wikipedia contributors, “Data provide linkages to the ADSs. quality,” Wikipedia, The Free En- All cadastral data cyclopedia, http://en.wikipedia. collections that do not Conclusion org/w/index.php?title=Data_ Unlike other spatial data (hydrography, quality&oldid=255796765 (accessed come from authoritative topography, orthoimagery, and the like), January 8, 2009). or trusted sources are cadastral data define rights and interests Wikipedia contributors, “Sys- in land, and how they are described and tem of record,” Wikipedia, The Free unofficial copies whose presented to the public can cause consid- Encyclopedia, http://en.wikipedia. erable confusion about value, ownership, value degrades over org/w/index.php?title=System_of_ and so on. Cadastral data are also unique record&oldid=237742899 (accessed because they are created and maintained January 8, 2009). time relative to the by more than 4,000 separate entities rate of updates to the across the country. Although the original FGDC Subcommittee for Cadastral business purpose of cadastral data is at Data, Cadastral NSDI Reference Docu- authoritative data. the local government level for assessment ment, p12, http://www.nationalcad. purposes, they have become critical to org/showdocs.asp?docid=158&navsrc= the efficient operations of many state and Report&navsrc2= Data Stewards national business operations because of Data stewards have the responsibility for their level of detail about the land and David Stage is a private consultant organizing, collecting, maintaining, and the currency of that information. Uses specializing in information manage- providing data. Data stewards are those vary widely, ranging from emergency ment and institutional and technical closest to the data creation—they have response and recovery, to environmental infrastructure issues that have to do recognized expertise in the field and fol- management, to health and safety, to with the use and sharing of cadas- low professional standards. In the realm of fleet management and more. As a result, tral data He has been the Eastern cadastral data, the land surveyor is the data there is a high demand for compiled and Cadastral Coordinator for the FGDC steward charged with collecting and inter- standardized cadastral information that Subcommittee for Cadastral Data preting information on the location and can be incorporated into a wide variety (Subcommittee) since 2002 working geometry of a parcel, and the county tax of applications. on projects to build a national spatial data infrastructure for cadastral data. assessor is the data steward charged with All cadastral data collections that do not Projects and publications cover a wide providing the valuation and related prop- come from authoritative or trusted sourc- variety of subjects that include the best erty information for the same parcel. es are unofficial copies or shadow data practices for state parcel management whose value degrades over time relative Authoritative Data Source programs, the acquisition of parcel to the rate of updates to the authoritative ADS is a term used by IT systems design- data in support of emergency response data. Unofficial data are often duplicative ers to define a process for ensuring the for hurricanes and wildland fire; ad- and create redundancy because they are data integrity in an application. When dressing issues for government to re-published data that are already avail- data are created or edited, data integrity government data sharing of cadastral able from a trusted source. Unofficial is preserved by providing a single object data between federal, state, local gov- sources create confusion among the gen- through which updates can occur. When ernments and the private sector. data are imported, which may be from eral public by providing un-maintained multiple sources, there is a strict vetting duplicative data and unofficial parcel-like Prior to working for the Subcommittee process to ensure the integrity of the data sets that can unexpectedly harm or he had been the State GIS Coordina- imported data. The process of managing damage property rights with inaccurate, tor for Florida from 1990 to 2001 and the updates of records, from the systems out-of-date information. the Florida Governor’s Liaison for the 2000 Census. designer’s perspective, results in authorita- Recognizing the importance of author- tive data. This is authoritative in a database itative sources for authoritative cadastral David Stage, [email protected] sense but not necessarily in a legal sense. data provided through a trusted source 850-668-2604

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