Survey of Ratio Study Methods Used By the States
|Frequency of Ratio Studies||Use of Sales||Use of Appraisals||Data Period
|Primary Measure of Assessment Level||Uniformity Measures||Reassessment Cycle (in Years)|
|Alabama||County, 67||Annual||Yes (b)||No||6 (c)||Median||COD (d)||5|
|Arizona||County, 15||Quarterly||Yes (e)||No||18-30||Median||COD/COV (f)||None|
|Arkansas||County, 75||Annual||Yes||Yes||12||Weighted Mean (g)||None||None|
|Colorado||County, 63||Annual||Yes (b)||Yes (h)||18||Median||COD/PRD (i)||2|
|Florida||County, 67||Ann/Bien(j)||Yes||Yes (k)||12||Weighted Mean (g)||COD||3 (visits|
|Georgia||County, 159||Annual||Yes||Yes||12||Median/Wtd. Mean (l)||COD/COV||None|
|Idaho||County, 44||Annual||Yes (e)||Rarely||12||Wtd. Mean/Median (m,g)||COD/COV/PRD||5|
|Illinois||County/Town, 969||Annual||Yes (b)||No||12||Median||COE/Coefficient of Concentration||4|
|Iowa||County, 111||Ann/Bien(n)||Yes||Yes (o)||12||Median (p)||COD||None|
|Kansas||County, 105||Annual||Yes (e)||Yes (k)||12 (c)||Median (g)||COD/PRD (g)||Annual Updates|
|Kentucky||County, 120||Annual||Yes||Yes (k)||6||Median (g)||COD||4|
Unincorporated areas, 488
|Annual||Yes||Yes (r)||12 (c)||Mean||COD||None|
|Massachusetts||City/Town, 351||Bien/Trien (s)||Yes (e, t)||Yes (u)||12 (c)||Median/Mean (v)||COD||3|
|Michigan||City/Town, 1527||Annual||Yes (b)||Yes (w)||24||Weighted Mean||COD/PRD||5 (Voluntary)|
|Minnesota||City/Town/Co., 2713||Annual||Yes||No||12/21 (x)||Wtd. Mean/Median (y)||COD/PRD||4|
|Mississippi||County, 82||Annual||Yes (e)||No||12||Median||COD/PRD||None|
|Missouri||County, 115||Biennial||No||Yes||N/A||Median (g)||COD/PRD||2|
|Nebraska||County, 93||Annual||Yes (e)||Yes (k)||18||Median||COD/PRD (z)||None|
|New Hampshire||City/Town, 259||Annual||Yes||No||12||Median||COD/PRD||None|
|New Jersey||City/Town, 567||Annual||Yes||No||12||2-Yr. Wtd. Mean||COD||None|
|New Mexico||County, 33||Annual||Yes||Rarely||12||Median||COD/PRD||2|
|New York||City/Town/Village/ County, 1241||Ann/Bien (aa)||Yes (bb)||Yes (cc)||12 (dd)||Wtd. Mean/Median (ee)||COD/PRD||None|
|North Carolina||County, 100||Annual||Yes||No||12||Median||COD||8 (ff)|
|North Dakota||City/Town, 1800||Annual||Yes||Yes (k, gg)||12 (c)||Median||COD/PRD||None|
|Ohio||County, 88||Triennial (hh)||Yes (e)||Rarely||36||Weighted Mean||COD/PRD||6 (ii)|
|Oklahoma||County, 77||Annual||Yes||Yes (k)||12||Median||COD||4|
|Oregon||County, 36||Annual||Yes||Rarely||12 (c)||Mean/Median/Wtd. Mean (jj)||COD/Av. Deviation||6|
|Rhode Island||City/Town, 39||Annual||Yes||Yes||12||Median||COD||10|
|South Carolina||County, 46||Annual||Yes||Yes (k)||12||Median||Index of Inequality||5|
|South Dakota||County, 66||Annual||Yes||No||24||Median||COD/PRD||None|
|Tennessee||County, 95||Variable (kk)||Yes||No||12||Median/Wtd. Mean (ll)||COD/PRD||4 or 6|
|Texas||County, 254||Annual||Yes||Yes||15||Weighted Mean (g)||COD/PRD||3|
|Utah||County, 29||Annual||Yes||Yes (mm)||18||Weighted Mean||COD/COV/PRD||5 (nn)|
|Vermont||City/Town, 251||Biennial||Yes||Yes (k)||24||Weighted Mean||COD/PRD||None|
|Virginia||County/City, 135||Annual||Yes||No||12||Median||None||2 city; 4 county|
|Washington||County, 35||Annual||Yes||Rarely||8||Weighted Mean||PRD||2, 4 or 6|
|West Virginia||County, 55||Quarterly||Yes||No||12||Wtd. Mean & Median||COD/PRD/M.W.(oo)||3|
|Wisconsin||Co./Town/Vlg., 1849||Annual||Yes||Yes||12||Weighted Mean||COD/PRD (pp)||5|
a. Units of local government which perform the assessing function.
b. Adjusted for financial terms.
c. Study period extended if valid sales are insufficient.
d. Coefficient of Dispersion.
e. Time adjusted.
f. Coefficient of Variation.
g. Uses confidence testing.
h. Agricultural class, and to supplement where sales are insufficient in other classes.
i. Price Related Differential (also known as the index of regressivity).
j. Annually tests whether each county is assessing within the permissible range of market value; biennially tests (half the counties per year) to determine the equitable distribution of state aid to schools.
k. To supplement where sales are insufficient.
l. The median is used by the Dept. of Revenue to test that the level of assessment meets statutory requirements. The weighted mean is calculated by the Audit Dept. to equalize values for school aid apportionment.
m. The weighted mean is calculated in one test to equalize values for school aid apportionment; the mean (or median) is calculated in a second test to adjust locally determined values, if necessary.
n. There are two purposes for the ratio studies done in Iowa. An annual test establishes equity among overlapping taxing districts and recipients of state aid. A biennial test equalizes all property classes in every assessing jurisdiction to the statutory level of 100% of true value.
o. Commercial and rural residential in biennial study.
p. A regression index is also calculated.
q. Selected property class studied in four-year period.
r. For residential and seasonal property only.
s. Biennial equalization study, triennial certification study.
t. Residential sales only
u. Audits in lieu of appraisals on non-residential property for triennial study; supplements with commercial/industrial appraisals for biennial study.
v. Uses median in triennial study; uses unweighted aggregate mean in biennial study.
w. Sporadic use of appraisals in commercial/industrial classes.
x. Twelve months for equalization purposes; 21 months for school aid purposes.
y. Uses weighted mean for state aid purposes; uses median for equalization purposes.
z. Both calculated only for residential property.
aa. Annual residential sales study, biennial equalization study.
bb. For residential sales study only.
cc. Used in equalization study only.
dd. Twelve months for residential ratio study; not applicable for equalization study.
ee. Uses weighted mean in equalization study; uses median in residential sales study.
ff. Some counties voluntarily revalue every four years.
gg. Appraisals are done by county directors.
hh. Semi-annual interim ratios issued.
ii. With updating in the third year of cycle.
jj. All three statistics are calculated by the state. Each county chooses which one is the best indicator for its array of ratios.
kk. Varies by each county's reappraisal cycle.
ll. Uses median for equalization purposes; uses weighted mean for update study purposes.
mm. Used for supplementing rural residential sales.
nn. With annual updates.
oo. Mann Whitney test.
pp. Also coefficient of concentration and frequency table.