104 MISC. PUBLICATION 218, U. S. DEPT. OF AGRICULTURE 
In the last analysis assessment is the result of personal judgment, 
based upon factual data in varying degrees. In fact the Supreme 
Court of Michigan has held that the assessment will rarely be 
invalidated if the assessing officials actually do exercise their best 
judgment, for “‘fraud cannot be predicated upon or inferred from 
an honest difference in judgment.” *’ The United States Supreme 
Court has said: 
The ascertainment of that value is not controlled by artificial rules. I¢ is 
not a matter of formulas, but there must be reasonable judgment having its 
basis in a proper consideration of all relevant facts.”8 
ASSESSMENT RATIOS 
DEFINITION AND SIGNIFICANCE 
The measure of the accuracy of an individual assessment is found 
in its relation to the legal standard. This relation is represented by 
the ‘“‘assessment ratio’’, which is the ratio, expressed in percent, of the 
assessed value to the true value (or whatever fraction of true value 
is the statutory basis of assessment).”” The assessment ratio of a 
group of properties—that is, the ratio of the aggregate assessed value 
to the aggregate true value, is equivalent to a weighted average of 
the individual assessment ratios and measures the level of assessment 
of the group. 
It follows from the above definition that absolute perfection in 
assessment would give to each individual property an assessment ratio 
of 100 percent. If all properties within a particular political district 
are assessed at practically the same ratio of true value—regardless of 
whether that ratio is 5, 50, or some other percent—there is impar- 
tiality between the taxpayers within that district so far as taxes levied 
by that district are concerned. But if the assessment ratios vary 
materially, the assessment and the consequent taxation favor the 
owners of properties having the lower ratios. 
Since all determinations of value are estimates, all assessment ratios 
are estimates. Since determinations of value for a group of properties 
are more accurate than for individual properties, a group assessment 
ratio is more accurate than the individual assessment ratios of the 
properties comprising the group. 
The testing of assessment practice by means of assessment ratios is 
by no means unique with this study. Tax officials in a number of 
States have made excellent use of such ratios as a basis for equalization 
among the taxing districts. The assessment ratio for such a district 
is usually determined on the basis of sample properties, taken as repre- 
sentative of the district as a whole, which have been either sold or very 
carefully appraised. The true or equalized value of taxable property 
in each district is then obtained by dividing the assessed value of the 
district or county by the appropriate assessment ratio. In Wisconsin 
the more accurate method is used of determining assessment ratios in 
each district by classes of real estate and weighting the ratio of each 
class by the total value of that class within the district in order to 
obtain the assessment ratio for the district. 
37 Lumber Co. v. City of Alpena, 176 Mich., 578. 
38 The Minnesota Rate Cases, 230 U. S. 434. 
29 The parenthetical clause relates to: Arkansas, whose statutory basis of assessment is fixed annually 
by the tax commission; Alabama, whose statutory basis of rural real estate assessment is 60 percent; Min- 
nesota, 3344 percent; Montana, 30 percent; North Dakota, 75 percent; Vermont, 1 percent; and Wash- 
ington, 50 percent. In Minnesota and Montana the percentage given does not apply to all real estate, but 
only to that class which includes forest property. 
