A Tool for Estimating Variability in Wood Preservative Treatment Retention

Composite sampling is standard practice for evaluation of preservative retention levels in preservative-treated wood. Current protocols provide an average retention value but no estimate of uncertainty. Here we describe a statistical method for calculating uncertainty estimates using the standard sampling regime with minimal additional chemical analysis. This tool can be used by wood treaters to generate lower prediction intervals that with a certain level of confidence give lower bounds on preservative retention estimates for a future analysis (e.g., by a customer) indicating whether the treated wood charge would result in a below-target retention value.