The department is required to provide an equalization factor for each county that will equalize the level of assessment at the statutory level of 33 1/3 percent of the fair cash value. The level of assessment to be equalized is the mean, or average, of the urbanweighted medians of the three years immediately preceding the assessment year, after adjustment for assessment changes through the current assessment year.
The urbanweighted levels of assessment for the three years involved in the calculation of the equalization factor are shown in Columns 2 through 4. These levels have been adjusted for assessment changes, including those made by any board of review for the current assessment year. Column 5 indicates the mean of the urbanweighted medians for the three years. Column 6 shows the final equalization factor and Column 7 shows the equalized level of assessment.
Sales Ratio  =  Prior Year Assessed Value Current Year Sale Price 
X 100% 

Coefficient of Dispersion (COD)  =  Average Deviation Median 
X 100% 
Median Absolute Deviation (MAD)  =  Median Deviation Median of Sales Ratios 
X 100% 
Coefficient of Concentration (COC)  =  Number of Sales Ratios within 10% of the median Total Number of Sales Ratios 

PriceRelated Differential (PRD)  
SalesBased Average Ratio  =  Sum of Assessed Values Sum of Sales Prices 
X 100% 
Mean Assessment Ratio  =  Sum of the Sales Ratios Number of Ratios 

PriceRelated Differential  =  Mean Assessment Ratio SalesBased Average Ratio 

Equalization Factor  =  Desired Level (33.33%) Prior 3Year Average Median Level 
Assessment  Sale price  Sales Ratio 
Absolute deviation from the median 


$ 9,000  ÷  $ 45,000  =  20%  15 
6,000  ÷  30,000  =  20%  15 
9,000  ÷  30,000  =  30%  5 
7,500  ÷  25,000  =  30%  5 
7,000  ÷  20,000  =  35%  0 
7,000  ÷  20,000  =  35%  0 
6,000  ÷  15,000  =  40%  5 
4,500  ÷  10,000  =  45%  10 
7,500  ÷  15,000  =  50%  15 
5,000  ÷  10,000  =  50%  35 
Total $68,500  $220,000  355%  85 
(derived from above data)
Number of Transfers:  10  

Median:  35 + 35 2 
=  35%  
First Quartile:  30%  Third Quartile:  45%  
Lowest ratio:  20%  Highest ratio:  50%  
Range:  (50%  20%)  =  30% 
Sum of absolute deviations from the median:  85  

Average absolute deviation:  85 ÷ 10 = 8.5  
COD:  Average absolute deviation Median 
= 8.5 ÷ 35% = 24.3% 