Statistical Reports
Based on the quality of data, AccuriZ can produce different statistical reports to provide a macro overview of a community or for specific purposes, detailed statistical
reports can be produced given specific levels of stratification. Some common statistical studies are as follows:
AccuriZ provides a scientific, unbiased approach for independent valuation. This approach is the culmination of years of experience and rigorous research using proprietary
series of algorithms to deliver the most accurate results- results that are not just close but precise.
AccuriZ follows a procedural structure aimed at delivering property valuation estimates that represent the most accurate market
value for the period defined. The most critical element in property valuation is the physical data that exists for a property.
Proprietary algorithms that have been developed over years of testing enable AccuriZ
to clean and stratify data so that accurate valuation estimates can be produced.
When operating in a vacuum, the absence of data yields
a poor valuation. At AccuriZ, we operate with precision, not in a vacuum.
Our analysis of property sales dating back to 1990 enables AccuriZ to develop
a powerful time-line covering the past 16 years. The reporting available as a result
provides real estate trends by zip code throughout New York State (and soon in other
regions as well).
4-3-2-1 Rule
An empirical rule that ascribes 40 percent of the value of a standard lot (see lot, standard)
to the quarter of the lot fronting on the street, 30 percent to the next quarter,
20 percent to the third quarter, and 10 percent to the rear quarter. Compare Harper
rule; Hoffman rule; one-third, two-thirds rule. Note: Lots with a depth greater
than the standard lot cannot be valued in accordance with this rule as stated above.
The rule is sometimes altered by omitting the word "standard." It thereby becomes
applicable to extra deep lots but produces inconsistent results as applied to lots
of varying depths.
65/35 Rule
Rule states that the value of a triangular lot with its base on the facing street will be approximately
65 percent of that of a rectangular lot of the same frontage and depth. The value
of the triangular lot with its apex on the facing street will be 35 percent of that
of a rectangular lot of the same base and depth.
Additive Model
A model
in which the dependent variable is estimated by multiplying each independent variable
by its coefficient and adding each product to a constant.
Adaptive Estimation
Procedure (AEP or Feedback)
A computerized,
iterative, self-referential procedure using properties for which sales prices are
known to produce a model that can be used to value properties for which sales prices
are not known. Also called "feedback."
Goodness-of-Fit
Statistics
Statistics
used in multiple regression analysis and other kinds of statistical modeling to
express the amount, and hence the importance, of the errors or residuals for all
the predicted and actual values of a variable.
Harmonic Mean Ratio
The reciprocal of the arithmetic mean of the reciprocals of each value in the data set. The harmonic
mean ratio is less affected by extreme values in the data set than the arithmetic
Kruskal-Wallis
Test
A test
in inferential statistics, valid for all types of numerical data, that seeks to
determine whether the observations in a sample came from one population as opposed
to three or more distinct, homogeneous subpopulations. This test is used in assessment
to analyze assessment ratios from three or more classes of property to determine
whether significant assessment biases are present among the classes of property.
When only two classes are being compared, the appropriate test is the Mann-Whitney
test.
Minkowski
Metric
Any of
a family of possible ways of measuring distance. Euclidean distance, a member of
this family, computes straight-line distances (as the crow flies) by squaring differences
in like coordinates, summing them, and taking the square root of the sum. In mass
appraisal model building, Minkowski metric usually refers to the sum of absolute
differences (not squared) in each dimension, and resembles a "taxicab" or city block
pattern. Other alternatives are possible, including the distance as calculated only
for the dimension of greatest difference, but the city block distance is most common.
Model
Calibration
The development
of adjustments, or coefficients based on market analysis, that identifies specific
factors with an actual effect on market value.
Multiplicative
Model
A mathematical
model in which the coefficients of independent variables serve as powers (exponents)
to which the independent variables are raised or in which independent variables
themselves serve as exponents; the results are then multiplied to estimate the value
of the dependent variable.
Multivariate Statistical Technique
Any of a number of statistical analysis in which data (such as the information on a single
property record card) containing a number of variables (such as lot size, number
of rooms, and construction type) are analyzed to predict the value of some other
variable. See also multiple regression analysis.
Observed Condition Breakdown Method
This divides depreciation into all its various components-curable physical deterioration, incurable
short-lived-item physical deterioration, incurable basic structure (long-lived items)
physical deterioration, curable functional obsolescence, incurable functional obsolescence,
and economic (external) obsolescence-often for each major building component.
One-Third, Two-Thirds Rule
An empirical rule that ascribes half of the value of a lot to the front third and the other half
to the rear two-thirds. Compare 4-3-2-1 rule; Harper rule; Hoffman rule.
Regression Coefficient
The coefficient
calculated by the regression algorithm for the data supplied that, when multiplied
by the value of the variable with which it is associated, will predict (for simple
regression) or help to predict (for multiple regression) the value of the dependent
variable. For example, in the equation, Value = $10,000 + $5,000 + number of rooms,
$5,000 is a regression coefficient.
Regression Line
The line on a graph that represents the relationship defined by the regression coefficients.
For example, the line from the relationship given in the definition of regression
coefficient would cross the y-axis at the value $10,000 and would go up $5,000 for
each movement of 1 to the right. This example illustrates one of the subtleties
required in understanding regression analysis: in fact, there is no line, because
the independent variable is not a continuous variable, but it is easier to talk
about the relationship by pretending that the variable is continuous and represent
the relationship by a line rather than the more nearly correct series of vertical
bars on a bar chart.
Regressivity
See assessment progressivity (regressivity).
Root Mean Square (RMS)
The square root of the average value of the sum of the squares of the differences between values
in a set and the corresponding values that have been accepted as correct or standard.
Used to measure map accuracy.
Zangerle Curve
A corner influence graph devised by John A. Zangerle, showing, for any given main street
frontage, the percentage of the side street value to be added as corner influence
to the value of the lot computed as an inside lot fronting on the main street. Compare
Bernard rule.
