In recent years wood strength researchers have begun to replace experimental unit allocation via random sampling with allocation via sorts based on nondestructive measurements of strength predictors such as modulus of elasticity and specific gravity. Although this procedure has the potential of greatly increasing experimental sensitivity, as currently implemented it can easily reduce sensitivity. In this paper we discuss the problem and we present solutions. Given the existence of nondestructive measurements of strength predictors, our methods can be used to reduce sample sizes. We have written a public domain computer program that implements the methods.

The Lake States of Michigan, Minnesota, and Wisconsin consist of 49.4 million hectares (122 million acres) of land, 19.8 million hectares (49 million acres) of which are forested, with 6% of those having been removed by law from timber production. Aspen (Populus tremuloides) is an important component of this resource. In recent years, a concern that the aspen cut will exceed its growth has surfaced. That is, Will the aspen supply be adequate to support the growing solid-wood, composite, and paper industries in the Lake States region? To satisfy the increased demand for forest products, it is expected that much of the future timber supply will be from improved trees grown on managed plantations. It is critical that the mechanical properties of this resource are clearly understood so that alternative uses of this material can be evaluated. A study was conducted using full-size lumber tests on 243 38- by 89-mm (2- by 4-in.; hereafter called 2 by 4 gass) boards cut, using two methods, from 50 logs to determine selected mechanical and physical properties of the Wisconsin-5 hybrid poplar clone. The material was either kiln dried or partially air dried followed by kiln drying. The 2 by 4 gass were assigned grades according to four grading rules: Light Framing, Structural Light Framing, Structural Lamination, and Machine Stress Rating. Results suggest that this poplar clone would produce visually graded material that is similar in properties and characteristics to the native aspen and cottonwood resource. Close to 65% of the material produced made grades of either Standard and better or No. 2. The Machine Stress Rating grade most likely to be produced from this material would be 1450f--1.3E. To avoid excessive degrade as a result of warping during drying, this material should be dried in flitch form.