Price Models for Small-End-Diameter Logs

Abstract

In this paper, new price models are developed for small-end-diameter logs, and their applicability is examined. In general, with a increase in diameter, a price of logs tends to be higher within a certain diameter range suitable for a pillar use. This relation between price and diameter can be expressed by a model with one peak in a price-diameter curve. Two types of the functional form are proposed for the function with a peak, i.e., the peak function. Applicability of these models is examined with use of five data sets for the price-diameter relationship of Ate lumber and sugi lumber from Noto district in Ishikawa prefecture, and hinoki lumber at Izumo district in Shimane prefecture. Our results show that these models fit the data well and are reliable for describing the relationship.