The value of parcel data begins to be built with the act of data collection. The study showed three issues associated with data collection that reduce this value from the very start: inconsistent numbering and indexing systems, inconsistent terminology used to describe key attributes, and factual errors introduced by inaccurate property transfer reports, and the inability of assessors to have complete access to privately owned property for appraisals.

All counties are required to have a parcel identification system which usually consists of a complex number denoting the section, block, and lot for a given parcel with respect to a historical land survey. However, counties and some municipalities can and do adopt different numbering and indexing systems and some systems work in such a way that the history of parcel sub-divisions cannot be traced by the use of the ID numbers. The lack of a uniform identification system statewide causes great difficulty for users who need to integrate data of different types, or match up parcels across the boundaries of different jurisdictions. Similarly, different municipalities and counties may use different terms to describe the same attribute leading to confusion about whether information from different jurisdictions is comparable.

In addition, the information that is reported about property sales is criticized by nearly every county and assessor. Most contend that buyers, sellers, and their attorneys pay little attention to the accuracy of the required report (the RP5217) which is filed with the deed in the County Clerk’s office. Because no enforcement mechanisms exist, these errors proliferate despite much work on the part of assessors and country RPTS staff to catch and correct them.

In addition, assessors report difficulty in obtaining complete and accurate property information because property owners can deny them access to buildings and other structures. In these cases, appraisals reflect the assessor’s best judgment rather than direct, detailed observation of the property. Errors are therefore introduced into the property record from the earliest point.