Waiting Lines Flashcards
What is a Queueing System?
Consists of a population of potential customers, a queue (waiting line), and a server.
What is a Finite Population?
A limited-size customer pool that will use the service and, at times, form a line. The size of the user group is reduced when a customer leaves the population.
What is an Infinite Population?
A population large enough so that subtractions or additions to the population do not significantly affect system probabilities.
What is the Arrival Rate?
The number of units arriving per period.
What is a Constant Arrival Distribution?
Periodic arrivals, with exactly the same time between successive arrivals.
What are Variable (Random) Arrival Distributions?
Arrival probabilities described statistically (e.g., exponential distribution for time between arrivals, Poisson distribution for the number of arrivals per unit time).
What is the difference between an Exponential and Poisson Distribution?
Exponential: time between arrivals
Poisson: number of arrivals per unit time
What are the two Sizes of arrival units?
single and batch arrival
What is Balking (impatient arrivals)?
Seeing the length of the line and leaving without ever waiting.
What is Reneging (impatient arrivals)?
Joining the line and later leaving due to a long wait.
What is Queue Discipline?
A priority rule or set of rules for determining the order of service to customers in a waiting line.
What is FIFO?
First-in, first-out; customers are served in the order they arrived (first come, first served).
What is Service Time?
The time the customer spends with the server once the service has started.
What is Service Rate?
The capacity of the server, measured in the number of units served per time period.
What is Single Channel, Single Phase (Line Structure)?
One server, one step in the service process.
What is Single Channel, Multiphase (Line Structure)?
One server, multiple steps in the service process.
What is Multichannel, Single Phase (Line Structure)?
Multiple servers, one step in the service process.
What is Multichannel, Multiphase (Line Structure)?
Multiple servers, multiple steps in the service process.
What is the Psychology of Waiting - Unoccupied time?
Feels longer than occupied time.
What is the Psychology of Waiting - Pre-process waits?
Feels longer than in-process waits.
What is the Psychology of Waiting - Anxiety?
Makes waits seem longer.
What is Psychology of Waiting - Uncertain waits?
Are longer than known, finite waits.
What is Psychology of Waiting - Unexplained waits?
Are longer than explained waits.
What is Psychology of Waiting - Unfair waits?
Are longer than equitable waits.
What is Psychology of Waiting - Valuable service?
The more valuable the service, the longer I will wait.
What is Psychology of Waiting - Solo waiting?
Feels longer than group waiting.
