Vintage Effects and the Diffusion of Time-Saving Technological Innovations: The Adoption of Optical Scanners by U.S. Supermarkets."

The diffusion literature implicitly assumes that a technological innovation remains homogeneous throughout the time period of the study with the sole modification being an assumed reduction in the real price of the technology over time. We argue that the technology can change in significant ways from one vintage to another to alter the nature of the diffusion process. We support this claim with estimates from non-parametric, semi-parametric and parametric duration models for the first generation of optical scanners installed in supermarkets in the U.S. between June 1974 and March 1985.