(a) The initial results of the sample estimate are analyzed in accordance with the following procedures. If the coefficient of variation is larger than a predetermined value, a supplemental sample is required. For purposes of this section, initial results shall mean the determinations of a coefficient of variation and supplemental sample as computed from the original survey data, regardless of the first use of the survey data, except that data changes subsequent to the original determinations that are incorporated into the survey data prior to, but not at the same time as, completion of the supplemental sample have the following effect:

1. (1) If the municipality, borough of New York City, Amityville or Wyandanch School District in the Town of Babylon, school district in a school district segment survey assessing unit, class in a special assessing unit or homestead assessing unit, school district designated in former 9 NYCRR section 186-6.1, as repealed in 1998 and set forth in section 1230 of the Real Property Tax Law in a homestead assessing unit or a special assessing unit or class in a portion in a special assessing unit or homestead assessing unit:

   1. (i) previously did not require a supplemental sample and the recomputed coefficient of variation does not exceed the survey limit, no additional samples are required;
   2. (ii) previously did not require a supplemental sample and the recomputed coefficient of variation exceeds the survey limit, additional samples are required;
   3. (iii) previously required a supplemental sample and the recomputed coefficient of variation exceeds the survey limit, new additional samples are required; or
   4. (iv) previously required a supplemental sample and the recomputed coefficient of variation does not exceed the survey limit, no additional samples are required.
2. (2) Data changes occurring in an assessing unit in a county where a supplemental sample was required, subsequent to the completion of the supplemental sample, or in an assessing unit in a county where no supplemental sample was required, more than two months after the determination of the coefficient of variation and supplemental sample, will not affect the determinations of a coefficient of variation and supplemental sample.

(b) The following operations shall be performed in the determination of the supplemental sample:

1. (1) Compute the coefficient of variation for each municipality, borough of New York City, Amityville or Wyandanch School District in the Town of Babylon, school district in a school district segment survey assessing unit, class in a special assessing unit or homestead assessing unit, school district designated in former 9 NYCRR section 186-6.1, as repealed in 1998 and set forth in section 1230 of the Real Property Tax Law in a homestead assessing unit or special assessing unit, and class in a portion in a special assessing unit or homestead assessing unit.

   1. (i) During the computation of the market value ratio estimate pursuant to this Subpart, the contribution to the coefficient of variation of the estimate, or CV, is also estimated for each value interval.
   2. (ii) For the computation of the coefficient of variation for a class in a special assessing unit, each “U” interval is assumed to have a relative sampling variance proportional to its corresponding special assessing unit class relative variance. For the computation of the coefficient of variation for a class in a nonspecial assessing unit or the Amityville or Wyandanch School District in the Town of Babylon, each “U” interval is assumed to have a relative sampling variance proportional to its corresponding municipal or school district relative variance.
   3. (iii) A coefficient of variation is not computed for the utility class. “S” intervals for the utility class are assumed to make no contribution to the sampling error since the intervals are not assigned their sample parcels by random selection methods.
   4. (iv) “T” intervals make no contribution to the sampling error.
   5. (v) All other “S” intervals contribute to the sampling error.
   6. (vi) The estimated coefficient of variation for each estimate is obtained by expressing the estimated standard error as a percentage of the ratio estimate.

2. (2) Determine the number of supplemental sample parcels necessary with respect to each municipality, borough of New York City, Amityville or Wyandanch School District in the Town of Babylon, school district in a school district segment survey assessing unit, class in a special assessing unit or homestead assessing unit, school district designated in former 9 NYCRR section 186-6.1, as repealed in 1998 and set forth in section 1230 of the Real Property Tax Law in a homestead assessing unit or special assessing unit, and class in a portion in a special assessing unit or homestead assessing unit.

   1. (i) If necessary, a supplemental sample is determined and the estimated coefficients of variation are tested in a multistep process. The order of the steps is as follows:

      1. (a) New York City:

         1. (1) municipal level estimate;
         2. (2) borough level estimate; and
         3. (3) special assessing unit class level estimates.

      2. (b) Nassau County:

         1. (1) city and town level estimate;
         2. (2) school district designated in former 9 NYCRR section 186-6.1, as repealed in 1998 and set forth in section 1230 of the Real Property Tax Law level estimate;
         3. (3) special assessing unit class level estimate;
         4. (4) city and town class level estimate;
         5. (5) village or town outside village class level estimate; and
         6. (6) school district class level estimate.

      3. (c) School district segment survey assessing units:

         1. (1) municipal level estimate; and
         2. (2) school district portion level estimate.

      4. (d) Homestead assessing units:

         1. (1) homestead assessing unit level estimate;
         2. (2) homestead assessing unit class level estimate;
         3. (3) school district portion designated in former 9 NYCRR section 186-6.1, as repealed in 1998 and set forth in section 1230 of the Real Property Tax Law; and
         4. (4) portion class level estimate.
      5. (e) For the Amityville or Wyandanch School District in the Town of Babylon, the school district level estimate.
      6. (f) For all other municipalities, the municipal level estimate.
   2. (ii) After the first step, the testing of the municipal estimated coefficient of variation, any hypothetical reduction to the CV attributed to any supplemental sample required in the first step or subsequent steps is assumed to have actually occurred prior to the test for the next step.
   3. (iii) At each step, the estimated coefficient of variation is compared to its corresponding CV limit shown herein.
   4. (iv) If the CV is greater than the appropriate CV limit, the sample size of the “S” interval contributing most to the CV is increased by one, the value interval contribution and CV are reduced hypothetically in accordance with sampling theory, and the adjusted CV is further tested against the CV limit. This process continues until a minimum number of supplemental samples have been assigned or the adjusted CV no longer exceeds the appropriate CV limit. If the initial CV estimate does not exceed the appropriate CV limit, no supplemental sample is assigned for the step. The minimum supplemental sample assigned for the municipal level estimate step is six, and for the village, borough, Amityville and Wyandanch School Districts in the Town of Babylon, school district in a school district segment survey assessing unit, and school district designated in former 9 NYCRR section 186-6.1, as repealed in 1998 and set forth in section 1230 of the Real Property Tax Law in a special or homestead assessing unit level estimate steps the minimum supplemental sample assigned is four. There are no minimums for the other estimates tested.

   5. (v) The CV limits for New York City are:

      	CV limit
      Municipal-citywide	2%
      Borough	3%

   6. (vi) For a class at the special assessing unit level, the CV limit is five percent.

   7. (vii) The CV limits for other assessing units are:

      1. (a) Municipal, the Amityville and Wyandanch School Districts in the town of Babylon, a school district segment survey assessing unit or a school district designated in former 9 NYCRR section 186-6.1, as repealed in 1998 and set forth in section 1230 of the Real Property Tax Law in a homestead assessing unit or special assessing unit.

         Estimated market value	CV limit
         0 to 49,999,999	5.0%
         50,000,000 to 99,999,999	4.8%
         100,000,000 to 199,999,999	4.6%
         200,000,000 to 299,999,999	4.4%
         300,000,000 to 399,999,999	4.2%
         400,000,000 to 499,999,999	4.0%
         500,000,000 to 599,999,999	3.8%
         600,000,000 to 699,999,999	3.6%
         700,000,000 to 799,999,999	3.4%
         800,000,000 to 899,999,999	3.2%
         equal to or greater than 900,000,000	3.0%

      2. (b) Portion class supplemental sample CV limits.

         Class	CV limit
         Homestead	7.5%
         Nonhomestead	7.5%
         A class other than class 3 in a special assessing unit	7.5%

3. (3) Sample parcels and possible alternates are randomly selected for each interval where additional sample parcels are required. Sample parcels are appraised in accordance with this Part.
4. (4) Recompute the estimated market value ratio in accordance with the procedures set forth in section 8186-24.9 of this Subpart, with the inclusion of the supplemental sample parcels.

(e) Commencing July 1, 1991, ORPTS shall review the initial survey results and determine the extent to which supplemental samples, if any, may be necessary. Subdivisions (a) through (d) of this section may be modified or superseded if the deputy commissioner determines that such action is necessary due to a lack of resources and available time to ensure completion of the entire survey by December 31, 1991. In such case the following CV limits shall apply:

1. (1) Municipal, the Amityville and Wyandanch School Districts in the Town of Babylon, a school district segment survey assessing unit or a school district designated in former 9 NYCRR section 186-6.1, as repealed in 1998 and set forth in section 1230 of the Real Property Tax Law in a homestead assessing or special assessing unit.

   Estimated Market Value	CV limit for Supplemental Sample
   0 to 49,999,999	6.0%
   50,000,000 to 99,999,999	6.0%
   100,000,000 to 199,999,999	6.0%
   200,000,000 to 299,999,999	6.0%
   300,000,000 to 399,999,999	6.0%
   400,000,000 to 499,999,999	6.0%
   500,000,000 to 599,999,999	5.8%
   600,000,000 to 699,999,999	5.6%
   700,000,000 to 799,999,999	5.4%
   800,000,000 to 899,999,999	5.2%
   equal to or greater than 900,000,000	5.0%

2. (2) Special assessing unit or portion class supplemental sample CV limits.

   Class	CV Limit for Supplemental Sample
   A special assessing unit class other than class 3 in a special assessing unit	5.00%
   Homestead or Nonhomestead	10.0%
   A portion class other than class 3 in a special assessing unit	10.0%