Since then, judges seem to have taken a figure of 10% (or, in some cases at least, perhaps 15%) of the true figure to constitute an area, or bracket, within which, prima facie, a valuation is not negligent. But the importance of that "bracket" notion must not be misunderstood. It is not a statement of some principle that no valuation within the bracket can, as a matter of law, be negligent. That such a valuation can still be negligent is not only a matter of common sense, but has been judicially developed in such cases as Interchase Corp Ltd v ACN 010 087 573 Pty Ltd (Supreme Court, Queensland, 520 of 1994, BC 200000188) [this appears to be a reference to [2000] QSC 013] and Lion Nathan Ltd v Coca-Cola Bottlers Ltd [1996] 1 WLR 1438. Once one finds that a valuation is within the "bracket", one can infer that prima facie, but only prima facie, it is not tainted by negligence; of course, it may have been arrived at by negligence, but that fact must be proved; one can never say that purely because a figure is within the "bracket", no negligence can be involved; but, on the other hand, if one arrives at a conclusion that a particular valuation is correct, one may turn to the "bracket" test as a check.
23 The plaintiff further relied on a decision of this Court in Trade Credits Ltd v Bailleu Knight Frank NSW Pty Ltd (1985) Aust. Torts Reports 80-757, wherein [at 69, 529] Clarke J relied on the various valuation evidence - other than that of the defendant valuer - in order to determine what a permissible margin of error was.
24 In a useful publication - A A Hyam, The law affecting valuation of land in Australia (Federation Press, 4th ed. 2009) one finds at page 190, the following passage in relation to the "use of comparable sales evidence":