N.Y. Comp. Codes R. & Regs. Tit. 20 §§ 8186-24.12

Current through Register Vol. 46, No. 50, December 11, 2024

Section 8186-24.12 - Methodology for stratification of sampled classes

(a)Definitions.

(1)Cost factor is a multiplier reflecting the relative cost of an average appraisal in an ordinary class in terms of the cost of a vacant land appraisal.

(2)Effective appraisal unit is equivalent to one sample parcel of average cost.

(3)Reldev is an adjustment factor based on previous class sampling error which shows the relative difficulty of sampling classes. A reldev is computed by multiplying the CV of an estimate by the square root of the sample size.

(4)Sample class means an ordinary class which is stratified with "S" intervals only. Excluded from a sampled class are large units ("T" intervals), unsampled intervals ("U" intervals) and the utility class.

(b)Determination of sampled class sample size, number of intervals, interval sample size and boundary and contents of interval.

(1) Determine survey unit total cost units by multiplying the number of parcels in each sampled class by the class cost factor and sum to the survey unit level and the special assessing unit level.

Sampled class	Sample class cost factor
1A and 1B	1.25
2A and 2B	4.00
4	3.30
A	1.30
B	2.90
C	1.20

(2) Determine initial sample cost units.

(i) For special assessing units, cities, towns, the Amityville and Wyandanch School Districts in the Town of Babylon and village homestead assessing units, calculate the square root of the total cost units for the special assessing unit or survey unit, add 25 and then multiply by the appropriate cost unit workload adjustment factor.

Assessing unit or school district	Cost unit workload adjustment factor
New York City	1.30
Nassau County	0.40
Cities and towns, other than special assessing units, and village homestead assessing units	0.74
Amityville or Wyandanch School District in the Town of Babylon	0.74

If the State equalization rate for the base year roll of cities and towns, other than special assessing units, or a village homestead assessing unit is less than 5.00, the cost unit workload adjustment factor is increased by 25 percent.

(ii) For a village school assessing unit first determine effective appraisal units from the following table:

Survey unit total cost units	Effective appraisal units
Less than 401	12 units
401 to 1,000	12 units, plus one additional unit for each 200 survey unit total cost units greater than 400
1,001 to 3,000	15 units, plus one additional unit for each 500 survey unit total cost units greater than 1,000
Greater than 3,000	19 units, plus one additional unit for each 1,000 survey unit total cost units greater than 3,000

(a) Multiply the effective appraisal units by the statewide weighted average cost factor for sampled classes, 1.41.

(b) Multiply the product from clause (a) by the cost workload adjustment factor of 0.85.

(3) Determine tentative class sample size.

(i) For special assessing units.

(a) Determine the estimated market value of each sampled class by dividing the assessed value of the class by the appropriate adjusted class market value ratio, computed from a prior survey and adjusted by the accumulated change in level of assessment from the base year roll of the prior survey to the base year roll of the current survey. Use the class 1 adjusted class market value ratio for classes 1A and 1B and the class 2 class market value adjusted ratio for classes 2A and 2B.

(b) Determine a survey unit class difficulty factor for each sampled class by multiplying the estimated market value of the class, calculated in clause (a), by the class reldev. For New York City there is a class reldev for each survey unit class and for Nassau County there is a class reldev for each special assessing unit class.

(c) Determine a survey unit weighted difficulty factor for each sampled class by multiplying each survey unit class difficulty factor, calculated in clause (b), by the square root of the class cost factor and summing the products to a survey unit level. In addition, for New York City determine a citywide weighted difficulty factor by summing the products to a citywide level.

(d) Determine the tentative sampled survey unit class sample size by dividing the survey unit class difficulty factor, calculated in clause (b), by the square root of the class cost factor and then dividing the resulting quotient by the survey unit weighted difficulty factor, calculated in clause (c). This result is then multiplied by the survey unit initial sample cost units and rounded to the nearest integer.

(e) For New York City, two additional calculations are required:

(1) Divide the survey unit class difficulty factor, calculated in clause (b), by the square root of the class cost factor and then divide the resulting quotient by the citywide weighted difficulty factor, calculated in clause (c). This result is then multiplied by the special assessing unit initial sample cost units and rounded to the nearest integer.

(2) Average the sampled class tentative sample size obtained in subclause (1) with the sampled class tentative sample size obtained in clause (d). The quotient is rounded to the nearest integer.

(ii) For cities and towns, other than special assessing units, the Amityville and Wyandanch School Districts in the Town of Babylon and village homestead assessing units.

(a) Multiply the total assessed value of each sampled class by the square root of the class cost factor, and sum to the survey unit level.

(b) Divide the total assessed value of each sampled class by the square root of the class cost factor.

(c) Divide the quotient obtained for each sampled class in clause (b) by the sum obtained in clause (a).

(d) Multiply the survey unit sample cost units by the percentage obtained in clause (c). The product rounded to the nearest integer is the sampled class tentative sample size.

(iii) For a village school assessing unit.

(a) Multiply the survey unit sample cost units by the percentage that each sampled class assessed value is of the sum of the assessed value of all sampled classes.

(b) Divide the product obtained in clause (a) by the appropriate class cost factor to determine initial sample size.

(c) Compare the initial sample size from clause (b) to the minimum class sample size shown in the following table. The larger sample size of the minimum sample size or the computed sample size is the sampled class tentative sample size.

Number of parcels in sampled class	Minimum sampled class sample size
1	1
2 to 4	2
5 to 7	3
8 to 199	4
200 to 999	6
1,000 to 1,499	8
Greater than 1,499	10

(4) Determine the number of "S" intervals in a sampled class.

(i) For New York City, cities, towns, the Amityville and Wyandanch School Districts in the Town of Babylon and village homestead assessing units, determine the initial number of "S" intervals in a sampled class from Table 1 below.

(a) If the number of parcels in the sampled class is less than 16 parcels, the initial number of intervals equals the number of intervals indicated in the table.

(b) If the number of parcels in the sampled class is greater than 15 parcels, the initial number of intervals is equal to the number of intervals indicated in the table minus one.

Table 1

Number of parcels in sampled class	Number of intervals	Minimum interval sample size
less than 7	1	Number of parcels
7 to 15	2	3
16 to 79	3	3
80 to 499	4	3
500 to 999	4	4
1,000 to 3,999	5	4
4,000 to 9,999	6	4
10,000 to 19,999	7	4
20,000 to 29,999	8	4
30,000 to 39,999	9	4
equal to or greater than 40,000	10	4

(ii) For Nassau County, determine the initial number of "S" intervals in a sampled class from Table 2 below.

(a) If the number of parcels in the sampled class is less than 20, the initial number of intervals equals the number of intervals in the table.

(b) If the number of parcels in the sampled class is greater than 19, the initial number of intervals equals the number of intervals indicated in the table minus one.

Table 2

Number of parcels in sampled class	Number of intervals	Minimum interval sample size
less than 13	1	Number of parcels
13 to 19	2	6
20 to 79	3	4
80 to 499	4	4
500 to 999	4	5
1,000 to 3,999	5	4
4,000 to 9,999	6	4
10,000 to 19,999	7	4
20,000 to 29,999	8	4
30,000 to 39,999	9	4
equal to or greater than 40,000	10	4

(iii) For a village school assessing unit.

(a) Determine the initial number of intervals from the following table:

Number of parcels in sampled class	Initial number of intervals
less than 8	1
8 to 49	2
50 to 199	3
200 to 399	4
400 to 599	5
600 to 699	6
700 to 799	7
800 to 899	8
900 to 999	9
greater than 999	10

(b) Compare the initial number of intervals determined from the preceding table to the result of dividing the sample size by two, and select the smaller of the two numbers as the number of intervals in the sampled class.

(5) Determine the boundaries and contents of "S" intervals.

(i) Sum the parcel assessed values in the sampled class from high to low, and test the sum after each parcel is added.

(ii) At each step in the process, test the cumulative assessed value of the interval being constructed against the result of the sampled class total assessed value, minus the cumulative assessed value of previously completed intervals, divided by the number of intervals left to be completed.

(iii) When the test indicates that, including the latest parcel added, the cumulative assessed value for the interval exceeds the test amount, the latest parcel is determined to be included in the interval, and the interval being processed is complete.

(iv) When an interval is complete, the interval total assessed value is subtracted from the sampled class test amount remaining to be assigned, and the count of intervals remaining to be constructed is reduced by one.

(v) This procedure continues until all parcels in the sampled class have been assigned to a value interval.

(vi) For identification purposes, the value interval which contains the parcel with the lowest assessed value is numbered "001." Subsequent intervals are identified from low to high by adding one to the previous interval identifying number.

(6) Determine boundaries and contents of subintervals.

(i) For special assessing units, cities, towns, the Amityville and Wyandanch School Districts in the Town of Babylon and village homestead assessing units.

(a) Examine the first value interval (S001) and determine the number of parcels that it contains.

(1) If the interval contains less than 15 parcels, or all the parcels in the original interval have the same assessed value, the boundaries and contents of the interval remain unchanged.

(2) If the interval contains 15 or more parcels with different assessed values, create two subintervals by comparing the assessed values of the parcels in the original interval to the mean assessed value of the original interval and assigning parcels, highest assessed value to lowest, to the higher subinterval until an assessed value not greater than the mean assessed value is found.

(3) The first parcel found with an assessed value not greater than the mean assessed value of the original interval, and all remaining parcels from the original interval, are assigned to the lower subinterval.

(b) For identification purposes, the subinterval which contains the parcel with the lowest assessed value is numbered "001." The second subinterval is numbered "002." Subsequent intervals are identified from low to high by adding one to the previous interval identifying number.

(7) Allocate class tentative sample size to "S" intervals.

(i) For special assessing units, cities, towns, the Amityville and Wyandanch School Districts in the Town of Babylon and village homestead assessing units.

(a) The class tentative sample size, rounded to the nearest integer, is divided by the number of intervals, resulting in an integer and a remainder. Interval sample sizes are then set, from the lowest value interval to the highest, equal to the integer plus one for the number of intervals equal to the remainder, and equal to the integer for any additional intervals.

(b) Compare the interval sample sizes from clause (a) to the minimum interval sample sizes shown in paragraph (4) of this subdivision; the larger sample size is the interval sample size.

(c) A sampled class in Nassau County which has greater than 19 parcels and two intervals has a minimum interval sample size of six. A sampled class in Nassau County which has greater than 19 parcels and three intervals has a minimum interval sample size of four.

(ii) For a village school assessing unit, determine the interval sample size in the manner described in clause (i)(a) of this paragraph. The sample size so determined for a given interval must be a minimum of two.

(iii) Where the interval sample size would be greater than the number of parcels in the interval, the interval sample size is equal to the number of parcels.

(iv) The sum of the interval sample sizes is the sampled class sample size.

(v) The sampled class sample size cannot exceed the number of parcels in the class.

(8) Pooling of intervals and sample sizes for a village school assessing unit.

(i) Examine each interval, from the highest numbered interval to the lowest, to insure that the interval passes either of the following tests:

(a) the interval sample size times two is not greater than the number of parcels assigned to the interval; or

(b) the interval sample size is not greater than the result of the number of parcels in the interval minus 10.

(ii) If the interval fails both tests, the interval is pooled with the next lowest interval by summing the number of parcels, assessed value and sample sizes for the two intervals.

(iii) Once an interval, or a pooled interval, passes either test, the testing ends for the sampled class.

N.Y. Comp. Codes R. & Regs. Tit. 20 §§ 8186-24.12