§ 1252. Manner by which ratios shall be determined. In determining
ratios pursuant to this article, the commissioner shall, for the last
completed assessment roll and each of the four preceding assessment
rolls, determine the ratio of assessed valuation to full valuation as of
the first day of January of the fiscal year for which the ratio is
applicable. Each ratio shall be determined on the basis of the market
value survey completed pursuant to article twelve of this chapter and
for which the valuation date is the first day of January of each
applicable year. In the event that a market value survey has not been
completed based upon each such valuation date, the commissioner shall
determine the ratios in the following manner:

(a) compute the ratio of assessed valuation to the full valuation of
taxable real estate on the basis of market value surveys completed
pursuant to article twelve of this chapter;

(b) on the basis of the ratios computed pursuant to subdivision (a),
project increases or decreases in the ratios for years for which the
information has not been developed pursuant to article twelve of this
chapter;

(c) avail itself of appropriate market value information appearing in
its office or acquired in the discharge of its duties pursuant to this
chapter.