EXPLORING THE ERROR STRUCTURE OF TAPER-EQUATIONS

Much work has been done fitting taper equations to specific tree bole shapes, but few researchers have investigated what effect the correlat ed error structure has on the fit of a taper equation. The Max and Bur khart (1976) taper equation was used in conjunction with a number of e quations which modeled the covariance structures. The equations propos ed were continuously differentiable, which simplifies the fitting proc ess, and selected to minimize the number of parameters. A maximum like lihood method was proposed to fit these equations and test the statist ical significance of the correlated errors. Accounting for the correla ted errors structure in the equation fitting process significantly imp roved fit. Tests showed a small, but significant, bias of 1.05% (+/- 0 .143%) when the correlated errors were ignored.