PRACTICAL METHODS FOR ESTIMATING NON-BIASED PARAMETERS IN SELF- REFERENCING GROWTH AND YIELD MODELS

Abstract

Since its inception in 1976, the primary objective of the Plantation Management Research Cooperative (PMRC) at the Warnell School of Forest Resources has been the development of growth and yield models for southern pines. Recent advances in computer and software technology have enabled the PMRC to explore the most computationally intensive data analysis methods. So-called traditional estimation techniques for dominant height projection equations involve the arbitrary choice of observed growth intervals and base ages, where each combination results in a different set of parameter estimates. Bailey and Clutter (1974) introduced the concept of base-ageinvariant site index equations. In this paper, we present two practical approaches to this estimation technique and compare their results to those obtained from traditional methodologies. The base-age-invariant techniques produced identical results regardless of the choice of base ages or applied algorithm. The traditional methods were notably affected by the choice of base age and measurement intervals.