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Table One
Sample Calculation of Weighted Mean Appraisal Ratio School District A: Single-family Residential
Sales
Sale
Number
Appraisal
Roll Value
Adjusted
Sale Price
Individual
Appraisal
Ratio
1 $65,834 $83,113 0.79
2 75,254 90,720 0.83
3 94,420 135,610 0.70
4 99,880 113,310 0.88
5 82,253 109,250 0.75
6 89,654 94,715 0.95
7 76,502 91,680 0.83
8 111,020 128,048 0.87
9 44,441 62,370 0.71
10 64,519 75,905 0.85
11 64,842 81,127 0.80
12 39,479 41,925 0.94
13 193,344 245,700 0.79
14 98,885 127,493 0.78
15 114,788 118,898 0.97
16 92,088 113,645 0.81
17 84,449 84,995 0.99
18 21,090 25,988 0.81
19 22,080 27,398 0.81
Appraisals
Appraisal
Number
Appraisal
Roll Value
Appraisal
Value for
Study
Individual
Appraisal
Ratio
1 $97,576 $110,741 0.88
2 60,437 70,964 0.85
3 107,543 148,828 0.72
4 60,264 86,303 0.70
5 69,708 76,117 0.92
6 76,935 98,327 0.78
Total Sales and Appraisals
  Total
Appraisal Roll
Value for Test
Total Value
of Sales and
Appraisals
Weighted
Mean
Appraisal
Ratio
  $2,007,285   ÷ $2,443,170   = 0.8216
  Total
Appraisal Roll
Value for Test
Total Value
of Sales and
Appraisals
Weighted
Mean
Appraisal
Ratio
  $27,621,400   ÷ 0.8216   = $33,619,036
Table Two
Sample Calculation of a Value-Stratified Weighted Mean Appraisal Ratio
(Step 1)
  Appraisal
Roll Value
in the sample
  Appraisal/
Sale Price
in the sample
  Ratio*
CAD/PTD
in the sample
STRATUM 1: $-0- to $2,500
Stratum 1 Total: not sampled   not sampled  
STRATUM 2: $1,205,000 and up
  1,205,000   1,210,000   0.9959
Stratum 2 Total: 1,209,961 ÷ 1,209,961 = 0.9959
STRATUM 3: $2,501 to $15,300
  11,243   8,000   1.4054
  13,510   10,000   1.3510
  14,194   11,500   1.2343
  14,800   12,000   1.2333
  15,001   13,000   1.1539
Stratum 3 Total: 68,748 ÷ 54,500 = 1.2614
STRATUM 4: $15,301 to $47,573
  20,374   20,000   1.0187
  20,477   20,000   1.0238
  20,994   20,000   1.0497
  25,806   24,800   1.0405
  28,166   27,000   1.0432
Stratum 4 Total: 115,816 ÷ 111,800 = 1.0359
STRATUM 5: $47,574 to $110,625
  51,007   52,000   0.9809
  52,191   52,000   1.0037
  53,217   54,000   0.9855
  54,141   54,000   1.0026
  57,396   57,000   1.0070
Stratum 5 Total: 267,952 ÷ 269,000 = 0.9961
STRATUM 6: $110,626 to $465,581
  111,648   125,000   0.8932
  114,140   135,000   0.8455
  139,498   150,000   0.9300
Stratum 6 Total: 365,286 ÷ 410,000 = 0.8909
Grand Totals: $2,022,802   $2,055,261    
totals based on 19 parcels
Mean Ratio (unweighted average)
average based on 19 parcels
1.0631
Weighted Mean Ratio
$2,022,802 / $2,055,261
0.9842
Price-Related Differential
mean ratio 1.0631 / weighted mean ratio 0.9842
1.0802
*Rounded 4 places

Table Three
Sample Calculation of a Value-Stratified Weighted Mean Appraisal Ratio
(Step 2)
Stratum
Number
Number of Parcels
in the
sample
CAD Value
in the
sample
÷ PTD Estimate
in the
sample
= Stratum Ratio
weighted mean ratio
in the
sample*
(#) (nsample) (TXsample)   (TYsample)   (r1sample)
1 n/a n/a   n/a   1.0000
2 1 1,205,000 ÷ 1,210,000 = census
3 5 68,748 ÷ 54,500 = 1.2614
4 5 115,816 ÷ 111,800 = 1.0359
5 5 267,952 ÷ 269,000 = 0.9961
6 3 365,286 ÷ 410,000 = 0.8909
*Rounded 4 places
Table Four
Sample Calculation of a Value-Stratified Weighted Mean Appraisal Ratio
(Steps 3-5)
Stratum
Number
Number of Parcels
in the
Stratum
CAD Value
in the
Stratum
÷ Stratum Ratio
weighted mean ratio
in the sample
= PTD Estimate
in the
Stratum**
(#) (Nstratum) (TXstratum)   (r1stratum)   (TYstratum)
1 711 300,224 ÷ 1.0000 = 300,224
2 1 1,205,000 ÷ census = 1,209,961
3 259 1,495,515 ÷ 1.2614 = 1,185,570
4 56 1,463,787 ÷ 1.0359 = 1,413,029
5 22 1,500,526 ÷ 0.9961 = 1,506,395
6 7 1,544,658 ÷ 0.8909 = 1,733,737
  ÷

÷

      +

  = =       =
  1,056 7,509,710   1.0219   7,349.099
  Total Total   (7,509,710 ÷ 7,349,060)   Total
  Stratum Parcels CAD Value   Stratified Ratio   PTD Estimate
**Rounded to the nearest dollar