Abstract: A method and apparatus for precisely controlling plastic strain rate during plastic deformation testing of a solid material such as a metal or plastic are described in which the effects of elastic strain rates associated with the specimens and machines used for such testing are eliminated by applying corrections proportional to the load on the specimen. Thus strain rate sensitivity, unaffected by the machine or specimen modulus can be measured. Strain rate sensitivity can be used to measure the activation volume of the specimen which may be used for quality control of material processing and/or manufactured articles.