This report discusses valid use of data produced by the Forest Service?s Forest Inventory and Analysis (FIA) program and used by the Northern Region of the National Forest System to analyze the compliance of individual National Forests with their Standards and Guidelines. It emphasizes use of FIA data on snag density and the percentage of forest area that meets the definition of old growth. This report does not give the results of such analyses. Rather, it gives the rationale for use of FIA data for such analyses.