Imputation and model-based updating techniques for annual forest inventories

The USDA Forest Service is developing an annual inventory system to establi sh the capability of producing annual estimates of timber volume and relate d variables. The inventory system features measurement of an annual sample of field plots with options for updating data for plots measured in previou s years. One imputation and two model-based updating techniques are describ ed and evaluated with respect to the bias and precision of their annual est imates of basal area per unit area. The evaluations indicate that simple pl ot-level imputation and model-based updating techniques produce adequately unbiased and precise estimates of annual mean basal area per unit area for large areas.