# Week 2 Flashcards Preview

## Operations Management > Week 2 > Flashcards

Flashcards in Week 2 Deck (21)
1
Q

What are the main characteristics of the queue?

A

Population source
Number of resources (servers)
Arrival & service patterns
Queue discipline

2
Q

What are the options for the potential number of customers?

A

Finite-source situation

Infinite-source situation

3
Q

What is a finite-source situation?

A

Potential number of customers is limited e.g. repairman responsible for x number of machines

4
Q

What is an infinite-source situation?

A

The potential number of customers greatly exceeds system capacity e.g. amusement centres

5
Q

What are the different channels of a system?

A

Single-server system and multiserver system

6
Q

What are phases in a queueing system?

A

e.g. theme park, people go from one attraction to another. Each attraction constitutes a separate phase where queues can form

7
Q

What is the distribution of arrival rate and service rate?

A

Poisson distribution for arrival and service rate

Negative exponential distribution for interarrival and service time

8
Q

What are the most common queue discipline?

A

FIFO (first-in-first-out) e.g. stores
Some are neither e.g. emergency room

9
Q

What are the assumptions of a single-server single-line single-phase system?

A
1. Customers are patient
2. Customers arrivals follow a Poisson distribution mean arrival rate of lambda, exponential distribution average 1/lambda
3. Customer service rate follow a Poisson distribution mean arrival rate of mu, exponential distribution average 1/mu
4. queue discipline is FIIFO
10
Q

What does rho mean?

A

The average utilization of the system

11
Q

What does L mean?

A

Average number of customers in the system

12
Q

What does Lq mean?

A

Average number of customers waiting in queue

13
Q

What does W mean?

A

The average time spent in the system, including serivce

14
Q

What does Wq mean?

A

The average time spent in queue

15
Q

What does Pn mean?

A

The probability that n customers are in the service system at a given time

16
Q

What extra assumption is there for the single-line, multiple server, single phase model?

A

All servers (s) are identical and have the same mu

17
Q

What does s mean?

A

Number of servers

18
Q

What are functional areas affected by waiting line decisions?

A

Accounting e.g. overstaffing
Marketing e.g. response time of service
Purchasing e.g. capital equipment capable of achieving the proposed service rate
Operations e.g. employee skill

19
Q

What type of changes can one make to the different elements of the waiting line system?

A

Customer arrival rates e.g. discount during nonpeak hours

Number and type of service facilities e.g. self-service checkout systems, number of cashiers, cash-only

Changing the number of phases e.g. Splitting task up between different servers (specialization)

Server efficiency e.g. grocery bagger or extra scanners

Changing priority rules e.g. multilane models (express lanes)

20
Q

System

A

group of objects that are joined together in some regular interaction or interdependence towards the accomplishment of some purpose

21
Q

Model validity

A

Making sure the conclusions you draw from the model are valid