Warranty cost analysis under continuous sales

The modeling and analysis of a variety of warranty policies and some related optimisation problems have been widely studied during the last decades. Recently, Blischke and Murthy proposed a new model for warranty servicing under continuous sales. However, we point out that there is a crucial mistake in their formulation, and provide a correct formulation. We illustrate the amounts of estimation errors using the numerical example of Blischke and Murthy.