Poststratification for increasing precision in forest inventory and analysis estimates in the Rocky Mountain states

Abstract

The U.S. Department of Agriculture’s Forest Inventory and Analysis (FIA) program provides nationwide estimates of forest resources. It is important that these estimates are both unbiased and precise. The portion of this inventory conducted in the Rocky Mountain states uses an ecological stratification layer to increase the precision of these estimates. This divides plots into groups where the response variable is more similar within each group than between the groups to help minimize the variance, which is equivalent to greater precision. Here we examine several potential new ecological layers. Historically, the ecological stratification was a layer of predicted forest and nonforest status. However, this layer was published in 2008 from 2001 data and has not been maintained or updated. To evaluate potential new ecological variance reduction layers, the standard deviations of the estimates of live basal area for the 280 counties within the 8 states in the Rocky Mountain region are compared. The final selection resulted in lowest standard errors in the majority of the counties and consists of high tree cover, low tree cover, and nontree strata. This new ecological layer is now in current use for increasing the precision of FIA estimates in all the Rocky Mountain states.

Citation

Freeman, E. A.; Bakken, J. L.; Moisen, G. G.; Toney, C.; Nelson, M. D.; Patterson, P. L. 2024. Poststratification for increasing precision in forest inventory and analysis estimates in the Rocky Mountain states. Res. Note RMRS-RN-102. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 121 p. https://doi.org/10.2737/RMRS-RN-102.