Strength tests have shown that the current visual grading system produces highly variable results. New nondestructive methods of stress grading have been found to be more efficient and have been introduced into commercial practice.

The statistical system is geared to automation and eliminates human judgment. It is also flexible to meet other future needs. Each piece is given a stiffness ratio; new wood species can be marketed for structural lumber; and higher strength material can be separated out for special uses.