Property characteristics driving real estate values

August 29, 2019 Michael Lomax

Over the years, the business landscape for property appraisers and assessors has been steadily evolving. While the utility of legacy systems such as CAMA continues to support the assessment process, the significance of data therein and its integrity has acquired a new dimension in this evolution. How can we empower assessors with accurate geo-enabled data to build more equitable valuations?

It is well understood within the industry that Assessment databases have vast amounts of characteristics/data. Maintaining this data is extremely difficult, time-consuming and often inequitable in application due to the extreme volume of properties. The maintenance and assurance of the accuracy and consistency of data over its entire life-cycle results in data integrity, which is a critical aspect to the design, implementation and usage of any system which stores, processes or retrieves data.

The International Association of Assessing Officers Standard on Mass Appraisal of Real Property also states:

“The accuracy of values depends first and foremost on the completeness and accuracy of property characteristics and market data. Assessors will want to ensure that their CAMA systems provide for the collection and maintenance of relevant land, improvement, and location features.(i)

The industry as a whole needs to find better, more efficient and equitable ways to perform data creation and data maintenance. How do we achieve that?

New technologies provide better answers

A Geographic Information System (GIS) permits graphic displays of sale prices, assessed values, inspection dates, work assignments, land uses and much more. In addition, a GIS permits high-level analysis of nearby sales, neighbourhoods and market trends; when linked to a CAMA system, the results can be very useful.(ii)

The question really is why linked to a CAMA system? The answer is that GIS and CAMA are separate systems requiring this “linking”. While GIS is a spatial (location-centric) solution, a real property database (CAMA) is not spatially influenced unless linked in some fashion. Often, linking results in minimal GIS capability other than the ability to display on the map. Assessment appraisers and/or assessors require location-based information and the ability to analyze not only the data integrity of the characteristics but also the contributory effects to value that the uniform application of characteristics allows.

During my days working as an assessor, I was often asked–either by a property owner or an appeal court–about how I came up with the specific effect to value that a view or a steep topography had on a property assessment. My stock answer and one common in the industry is that it was based on my review of sales information coupled with my domain expertise as a real estate appraiser. Obviously, that type of answer can be enhanced, but at the time there was little evidence, science or capability allowing me to be more precise and objective. This was true then, and still in use today, however…is it time for us, as an industry, to start integrating newer technologies into our workflows and create a more efficient framework for assessments?

A Geographic-Assisted Mass Appraisal system

Back to my point about the two key systems in use today, being 1) CAMA and 2) GIS; the question arises why are they not just one single database? A CAMA system allows for the storage, retrieval and administration of land and property records, whereas GIS allows for spatial reference to data and the subsequent analysis of that data. Shouldn’t they be just ONE system? Isn’t that the evolution of real  property databases worldwide? 

Today GIS and CAMA can be one system of record where the advantages of both systems are exploited in one database. This allows more objective and less subjective maintenance of data while allowing spatial analysis of the contributory effects of property characteristics on the overall assessed value.  With regards to my point about value effects of things such as view and topography, with this one single database approach, the capability exists to scientifically analyze the actual 3D viewsheds and topography. Since it is a single database, the contributory effects can be easily quantified and valued within the valuation model. This is the new paradigm of Geographic Assisted Mass Appraisal (GAMA).

Viewshed Analysis in 3D – Physically & Spatially correct building

Topography / Slope calculations from Digital Elevation Model

What do you think?  Do you want to discuss this further? I’d be happy to take on questions and brainstorm about possibilities at our upcoming International Association of Assessing Officers Annual Conference in Niagara Falls – Booth 201 from Sept 8-11, 2019, where we will be demonstrating the use of Assessment Analyst® - GAMA and how it can help Assessment Jurisdictions create, maintain and analyze property characteristics in a single GAMA database. Join us for our presentation:

Esri Canada CAMA to Geographic Assisted Mass Appraisal "GAMA"
Sept 10, 1:30 pm to 2:30 pm
Location: Room 222


[i] https://www.iaao.org/media/standards/StandardOnMassAppraisal.pdf

[ii] https://www.iaao.org/media/standards/StandardOnMassAppraisal.pdf

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