A note on calculating cost of two-dimensional warranty policy

We study the derivation of warranty cost under rectangular two-dimensional policy for both repairable as well as non-repairable product. Typically, two approaches are adopted, namely, one-dimensional (1D) and two-dimensional (2D). We show the difference in results obtained from the formulae under the two approaches through several examples. Merits of the formulae are then analyzed to identify the correct ones.