• warranty claims;
  • multistate components;
  • sales delay;
  • failure rate;
  • non-homogeneous Poisson process

Sales delay is the time interval from the date of manufacture to the date of sale. In analysing warranty claims data, the existing research relating to the sales delay has mainly focussed on estimating the probability distribution of the sales delay. Longer sales delay may lead to more warranty claims as it can affect the post-sale reliability of products. However, research into this problem has received little attention.

This article estimates the expected number of warranty claims under both renewing and non-renewing warranty policies taking into account the sales delay. We consider the case with three states, the sales delay state, the operating state and the failed state. We extend the three-state case into an n state system case, where n ⩾ 3. We then give numerical examples to demonstrate the application of the derived equations. We also present a simulation and a case study where we estimate the reliability of products with three states. Copyright © 2012 John Wiley & Sons, Ltd.