This significant and timely new ASTM publication explores the problems involved with the inherent limitations that are present in all test methods. These limitations, caused by numerous variables, have a direct influence on the accuracy of the generated test data. This volume demonstrates how to properly use and select test methods for specific applications, and how to better understand the generated test data. 17 peer-reviewed papers are divided into the following sections: • General Design — discusses the various options and concerns facing engineers in the selection of the best material candidate and the development of test data for a specific performance criteria. Two methods for estimating lifetime expectancy under non-isothermal conditions are also examined. • Mechanical — explores traditional tests such as tensile and deflection under flexural load. This section investigates common variables that affect test results in both ASTM and ISO tensile tests, and the implications of conversion from ASTM to ISO standards for material characterization. Also covered are new techniques for testing adhesive bond strength tests for piping systems. • Impact/Fracture — examines the large number of variables that have a significant effect on impact resistance, including data comparing instrumented and non-instrumented IZOD and Charpy tests. It also presents a new standardized test procedure and round robin test data developed over a five-year period validating the test protocol. • Chemical/Rheological — covers advanced testing techniques primarily in the area of rheological testing. Included is a presentation comparing thermomechanical analysis to the coefficient of linear thermal expansion and the measurement of the glass transition temperature. Audience: Technicians and managers in plastics testing laboratories. Also for sales and marketing personnel who use test data and anyone in corporate management who needs an understanding of the limitations of generated test data.