Today, the availability of design of commercially of the shelf (COTS) design software has greatly simplified the design and analysis of infinite impulse response (IIR) digital filters. The successful implementation of a fixed-point IIR, however, remains problematic. The fundamental problem is controlling degrading finite wordlength effects, which can take the form of damaging run-time register overflow and arithmetic roundoff errors. The severity of such effects is directly influenced by a number of choices, including filter architecture and arithmetic precision. State variables provide a means of facilitating the analysis of finite wordlength effects in the context of specific architectural choices. In this paper, IIR design methodology, state variables, and finite wordlength analysis techniques are fused together to define a viable fixed-point IIR design outcome.