Error bounds on a practical approximation for finite tandem queues

A simple practical approximation is studied for a two-stage tandem queue with a finite first station. Explicit small error bounds are obtained for the mean queue length and the tail probabilities of the second queue. These error bounds are based on a new application of an existing error bound theorem for comparing Markov chains. The extension requires the so-called bias-terms to be bounded by a bounding function that can be unbounded or oppositely become small. The extension is of interest for further exploitation.