ABSTRACT
A queue is observable if customers know its length either by direct observation it or by indirect inference. For example, queue length can be inferred from state-dependent (dynamic) price quotes of the server. Otherwise the queue is unobservable. The rational queueing literature mostly deals with unobservable queues, and this fact is often taken for granted without being explicitly mentioned. The main reason for focusing on unobservable queues is, probably, that they are easier to analyze than observable queues. Yet, observable queues carry with them unique interesting features.
