AVM Glossary

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  • A particular statistic important in inferential statistics for certain kinds of hypothesis testing of certain kinds of data.
  • A particular parametric statistical test useful, among other things, in testing the level of assessment.
  • See depth table.
  • See property.
  • A compulsory charge levied by a government unit against the income or property of a person, natural or corporate, for the common benefit of all citizens. The term does not include specific charges made against particular persons or property for current or permanent benefits and privileges accruing only to those paying such charges, such as licenses, permits, and specific assessments.
  • A tax levied on a base that is measured by value. Note: This term is often used to refer only to property taxes or to general property taxes, although technically it is applicable to income taxes, ad valorem tariffs, special property taxes, and so on. Contrast tax, specific.
  • A Valuation Method that provides an estimate of value as a function of the tax assessed value by applying a multiplier or other adjustment to the tax assessed value.
  • Derive an estimate of value by examining market values attributed to properties by the local taxing authorities. As a matter of local law and custom, the values reported by the taxing authorities often (but not always) vary from the current market value in some reasonably predictable manner. For example, some jurisdictions require the taxing authority to report the value at 25 percent of estimated market value. In others, values are reassessed only on an infrequent basis. Some jurisdictions report multiple values - Assessed, appraised, and market values. By examining local laws and(...)
  • Tax assessment models estimate market value based on local taxing authorities’ annual (often less than annual) evaluations of properties located within their jurisdictions. These models do not function in Proposition 13 states.
  • See assessment, special.
  • Economic costs or losses resulting from the imposition of a tax. Burden can be determined only by detailed economic analysis of all economic changes resulting from the tax. In popular usage, the term often refers to the initial incidence rather than to ultimate economic costs.
  • (1) In general, a state or any political subdivision thereof having or exercising the power to levy taxes. (2) As applied to property taxes, any area, whether coterminous with or within a state or a political subdivision thereof, within which the tax rate levied by such state or political subdivision is required by law to be uniform on properties of the same class.
  • Originally, an ad valorem property tax that, in contemplation of law, was administered uniformly with respect to all tangible and intangible property (with the exception of a few classes specifically exempt) and that involved a uniform rate throughout each tax district.  (2) Currently, the remnants of such a tax after its continued curtailment through classification, exemptions, use-value assessment laws, and special property tax laws applicable to various types of personal property.  Compare tax, special property; tax, classified property.
  • Any tax that is imposed on persons on account of their ownership or possession of property and is measured by the number of units, the value, or some presumptive evidence of number of units or value, of such property. Note: This tax is generally, but not necessarily, intended to be a direct, proportional ad valorem tax. Compare tax, general property; tax, special property; tax, classified property.
  • A tax in which the effective tax rate is the same for all taxpayers regardless of the sizes of the tax bases on which they are subject to taxation. Contrast tax, progressive; tax, regressive.
  • (1) The amount of tax stated in terms of a unit of the tax base, for example, 30 mills per dollar, 2 percent, 2 cents per gallon. (2) For the property tax, the percentage of assessed value at which each property is taxed in a given district. Distinguish between effective tax rate and nominal tax rate.
  • (1) A tax in which the effective rate is higher for a taxpayer subject to taxation on a small tax base than for a taxpayer subject to taxation on a large tax base. (2) Loosely used to refer to any tax that absorbs a smaller proportion of the wealth or income of the well - To - Do classes than of the poorer classes. Note: A tax is said to be regressive in administration, though not legally regressive, when the ratio of the actual base to the statutory base declines as the statutory base increases, in such manner as to nullify a proportional statutory rate or to make a progressive(...)
  • An official list showing the amount of taxes charged against each taxpayer and/or each property within the jurisdiction of a tax district. Note: In property taxation, the tax roll is sometimes combined with the assessment roll into a single document.
  • A convenient way to group the various methods of appraising a property. The cost approach encompasses several methods for estimating replacement cost new of an improvement less depreciation plus land value. The sales comparison approach estimates values by comparison with similar properties for which sale prices are known. The methods included in the income approach are based on the assumption that value equals the present worth of the rights to future income.
  • The price at which a property sold, adjusted for the effects of price changes reflected in the market between the date of sale and the date of analysis.
  • A family of techniques that can be used to measure the cyclical movements, random variations, seasonal variations, and secular trends observed over a period of time.
  • An acceptable margin of error or inaccuracy.
  • Refers to the basic description and elevation of a piece of land.
  • The contour of land surface, for example, gently rolling, mountainous, or flat.
  • The period of time or units of production over which the operation of an asset is economically feasible, not necessarily the same as its physical life.
  • The dataset used to fit (estimate the parameters of) a model (AVM). See also "Sample," "Representative Sample" and "Population."
  • The transaction associated with the Reference Value (e.g. purchase, cash-out refinance, rate-term refinance).
  • Adjusting the values of a variable for the effects of time. Usually used to refer to adjustments of assessments intended to reflect the effects of inflation and deflation and sometimes also, but not necessarily, the effects of changes in the demand for microlocational goods and services.
  • A figure representing the increase in cost or selling price over a period of time. Trending accounts for the relative difference in the value of a dollar between two periods.
  • The arithmetic mean of a data set identified by the proportion of the sample that is trimmed from each end of the ordered array. For example, a 10 percent trimmed mean of a sample of size ten is the average of the eight observations remaining after the largest and smallest observations have been removed.


a)       AVMetrics

b)      AVMs 201: A Practical Guide to the Implementation of Automated Valuation Models, Jim Kirchmeyer, 2008.

c)       IAAO 2015, Glossary for Property Appraisal and Assessment, 2015. (2013 online: https://www.iaao.org/media/Pubs/IAAO_GLOSSARY.pdf )

d)      Collateral Assessment & Technologies Committee, Summary of Definitions & Terms, 2006.

e)      Joint Industry Task Force on AVMs, IAAO Standard on AVM Glossary, September 2003. https://www.iaao.org/media/standards/AVM_STANDARD.pdf

f)        Appraisal Institute, Joint Industry Task Force on Automated Valuation Models, Work Group Terminology, 2005.

g) Merriam-Webster (https://www.merriam-webster.com/)