A TEST OF ALTERNATIVE ESTIMATORS FOR VOLUME AT TIME-1 FROM REMEASUREDPOINT SAMPLES

Two estimators for volume at time 1 for use with permanent horizontal point samples are evaluated. One estimator, used traditionally, uses o nly the trees sampled at time 1, while the second estimator, originall y presented by Roesch and coauthors (F.A. Roesch, Jr., E.J. Green, and C.T. Scott. 1989. For. Sci. 35(2): 281-293), takes advantage of addit ional sample information that becomes available at time 2. In this tes t the Roesch et al. estimator was always lower in sum of squared diffe rences and sum of absolute differences for board foot and cubic foot v olume than the traditional estimator. In addition a simulation reveale d no discernible bias for the Roesch et al. estimator over the traditi onal estimator.