In Arizona Department of Revenue v. Trico Electric Cooperative, 151 Ariz. 544, 729 P.2d 898 (1986), the Department valued an electric utility's property according to a statutory formula. The utility, Trico, complained that the Department had not used standard appraisal methods and techniques to calculate obsolescence after applying the statutory formula. Id. at 546, 729 P.2d at 900. Ultimately, the Arizona Supreme Court upheld the value produced by the statutory formula, explaining that "the legislature intended the statutory formula . . . to be the exclusive method used to calculate full cash value of electric and gas utilities." Id. at 547, 729 P.2d at 901. The very definition of "full cash value" states that it is to be determined by statute. Id. at 546, 729 P.2d at 900.