The 'bracket test' (10-15% of the true figure) in valuer negligence cases creates only a prima facie inference of non-negligence, not a rule of law precluding a finding of negligence. A valuation within the bracket may still be negligent if that is proved. The bracket test is properly used as a confirmatory check after an independent finding that the valuation is correct, not as the sole basis for a finding of non-negligence.
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