§ 1, at 2 [July 20, 2004]). As a result, we do not find unreasonable the assertion that "$2.5 billion in additional revenues statewide (equating to $1.9 billion in New York City) was a valid determination of the cost of providing a sound basic education in New York City" (State Education Reform Plan, at 14 [Aug. 12, 2004]). There is substantial record support for that statement. First, the use of the cost-effectiveness filter is rationally defensible. The variation in spending between New York school districts is very large.[FN5] As S & P explained, averaging the expenditures of all successful schools would [*11]"mask a considerable range of per-pupil spending among the individual districts . . . If the concept of 'adequacy' means spending no less, but not necessarily more, than is necessary to produce high achievement levels, then there is reasonable cause to adjust the base expenditure by a measure of cost effectiveness. This can be done by ranking the successful districts under each scenario by their base expenditure, and computing the average of the lowest 50% (in terms of spending), which is the same approach used by the New York Board of Regents in its recent study of educational costs. An analysis of the average achievement levels of the lower-spending half of districts shows that they closely resemble the average achievement levels of the upper-spending half of districts . . . ." (Standard &{**8 NY3d at 31} Poor's Resource Adequacy Study for the New York State Commission on Education Reform, at 46-47 [Mar. 2004].) The essential premise of the cost-effectiveness filter is that the higher-spending half of the successful districts is spending more than the constitutional minimumeither because those districts spend less efficiently than some others or because they have chosen to do more for their students than the Constitution requires. The State, in adopting S & P's approach, implicitly concluded that New York City could attain minimal constitutional standards while spending less than this higher-spending group of successful districts. The premise, and the conclusion, are no doubt debatable, but we cannot say they are irrational, and they are therefore entitled to deference from the courts. The S & P weightings for children with special needs also have record support. While S & P did not recommend any particular weighting over another, the coefficients that S & P applied were drawn from an extensive review of relevant research. Indeed the pertinent footnote to S & P's Resource Adequacy Study cites no fewer than 37 articles, reports and other scholarly works (Standard & Poor's Resource Adequacy Study for the New York State Commission on Education Reform, n 16, at 89-92 [Mar. 2004]). The S & P calculationsapplying a 2.1 weighting for students with disabilities, 1.35 for economically disadvantaged students, and 1.2 for students with limited English proficiency, and reaching the conclusion that the spending gap for the New York City School District is $1.93 billionwere reasonable. Although we recognize that legitimate arguments can be made for raising the coefficient for economically disadvantaged students to 1.5, we do not believe that the figure of 1.35 lacks grounding in prudent reason.