Wednesday, October 19, 2016

Parcel Data - Authoritative Source and Fitness for Use

The authoritative source for parcel data depends on what type of parcel data.  For tax parcels, the most commonly aggregated and distributed data set, the real estate taxing authority that created them (see who builds parcel data) is the most widely accepted authoritative source. For legal survey boundaries, the land survey record is the authoritative source.  But do we really mean fitness for use?

Authority, authoritative, and authoritativeness always seem to trigger a fairly robust discussion, especially around cadastral data.  A few dictionary-based definitions may be a good starting point.  The following are gathered from various dictionaries and papers on this topic.

Authority and Authoritative - Authoritative is recognized as trustworthy, competent, reliable, and true.  Supported by an authority.  In the context of public agencies it is the legal responsibility provided by a legislative body to conduct business for the public good.

Official - A person invested with the authority of an office.

Authoritative Data – For publicly sourced data these are officially recognized data that can be certified by the public provider, such as a certified tax roll, and is provided by an authoritative source.

Authoritative Data Source – An information technology (IT) term used by system designers to identify a system process that assures the veracity of data sources. All geospatial data providers should follow these IT processes. The data may be original or it may come from one or more external sources all of which are validated for quality and accuracy.

Authoritative Source – An entity that is authorized by a legal authority to develop or manage data for a specific business purpose. The data this entity creates is authoritative data. Authoritative data comes directly from the creator or authoritative source. It is the most current and accurate and has been vetted according to official rules and policy. The data has a known accuracy and lineage and can be verified and certified by data stewards in the authoritative source. In some terminology this is termed the “primary” data source or the “official” data source.

Authorization The result of an act by a legislative or executive body that declares or identifies an agency or organization as an authoritative source or grants the rights to an agency to act, such as an authorization to manage land or collect information.

Data Steward – An organization within an authoritative source that is charged with the collection and maintenance of authoritative data. The term data steward is often confounded with the term authoritative source. A data steward may be a designated point for the assembly and aggregation of data from authoritative sources.

Trusted Source and Trusted Data – A service provider or agency that publishes data from a number of authoritative sources. These publications are often compilations and subsets of the data from more than one authoritative source. It is “trusted” because there is an “official process” for compiling the data from authoritative sources and the limitations, currency, and attributes are known and documented.

In the discussions around a national parcel data set or national parcel data sources, It appears that a discussion and agreement on fitness for use, including some standard or consistent wording or perhaps even categories of fitness for use would come in handy.  We need to answer questions such as “are the values on this parcel from my local assessor and are they official or certified?” or “can I rely on these annexation boundaries as the official boundaries?” or “are these boundaries attached to their definitive source document?” Standard metadata templates include a field for describing intended use or use limitations.  Perhaps it is time to look at providing consistency for these fields.

Many local and state published data sets have a disclaimer that limit the liability of the publisher and provide some general fitness for use such as “not to be used for land transaction legal descriptions”.   A data publisher can never know all possible uses for a data set.  It is likely that some or most data sets will be misused.  Disclaimers try to limit the liability of the data producer if the data are put to some unintended or wholly inappropriate use or relied upon to support an application for which the data was never intended.  This is completely understandable.

As parcel data moves to more open formats and publication, perhaps this is a good time for the community to have some discussions and consensus on expected fitness for use.  This would be more exact and less misunderstood than using terms like authoritative or trusted.