Contemporary efforts to conserve populations and species often employ population viability analysis (PVA), a specific application of population modeling that estimates the effects of environmental and demographic processes on population growth rates. These models can also be used to estimate probabilities that a population will fall below a certain level. This information is helpful in understanding the threat of a species' extinction from environmental and demographic factors.
Sieg, Carolyn Hull; King, Rudy M.; Van Dyke, Fred. 2003. Creating a stage-based deterministic PVA model - the western prairie fringed orchid [Exercise 12]. In: Van Dyke, Fred, ed. A Workbook In Conservation: Solving Practical Problems in Conservation. New York, NY: McGraw-Hill. p. 91-99.