Regarding the editorial “Why the broad disparities in Butler school appraisals?” (Sept. 25)

In Pennsylvania, the law requires that certified real estate appraisers meet educational, experience and testing requirements. The two appraisers engaged by the School Board not only have met the state requirements, but also are a candidate and designated member, respectively, of the Appraisal Institute, the nation’s largest professional association of real estate appraisers.

The Appraisal Institute has additional standards and ethical requirements for their professionals. These requirements are intended to provide even higher protection of the public served by these individuals.

Appraisers make use of many analytical methods and techniques. Applying these techniques and interpreting the data is an art, not a science. As such, it is not uncommon for two appraisers’ opinions to vary widely, especially when considering a limited-market property, i.e., properties of a type that has relatively few potential buyers at a particular time, such as schools. Due to the relative small markets and lengthy market exposure needed to sell such properties, there may be little evidence to support an opinion of market value. The appraiser must rely on personal judgment in addition to any direct market evidence available.

Finally, it’s important for the client to have each appraisal properly reviewed. In this case, the appraisal review would be performed to determine the credibility of the value conclusions and the adequacy of the supporting evidence provided.