## Different Operations Research Models

Q: Give brief outlines of OR-Models.
OR

Write a note on applications of various quantitative techniques in different fields of business decision making.

Answer: Following is a list of a few important OR models or Quantitative techniques of operations research:

Distribution (Allocation) Models
Production / Inventory Models
Waiting Line or Queueing Models
Markovian Models
Competitive Strategy Models (Game Theory)
Network Models
Job Sequencing Models
Replacement Models
Simulation Models

Distribution (Allocation) Models
A distribution model uses mathematical programming techniques (linear or non-linear programming)to deal with an allotment of available resources so as to minimise cost or maximise profit subject to prescribe restrictions. Transportation and assignment models can be viewed as special cases of linear programming.

Production / Inventory Models
Inventory models are concerned with the determination of the optimal order quantity and ordering intervals considering various factors like demand per unit time, costs of placing orders, costs associated with goods, inventory costs due to the shortage of goods etc. Production models are useful for handling quantity discounts and multiple products.

Waiting Line or Queueing Models
Queueing models help in predicting how much average time spent by the customers in a queue or average length of a waiting line etc. The models help to minimise the sum of costs of providing service with respect to the time spent by customers in a queue.

Markovian Models
Markovian models are very useful in those systems where the state of the system moves based on probability. e.g. brand switching problems in marketing studies.

Competitive Strategy Models (Game Theory)
These models compute the behaviour of decision making under conflict or competition. Game theory is mainly used in fields related to economics, political science, and psychology.

Network Models
These models are widely applied in enterprise projects that involve interdependent activities. PERT (Project Evaluation and Reviewing Techniques) and CPM (Critical Path Method) are used in project planning, scheduling and controlling the project.

Job Sequencing Models
These models help in computing the efficiency of machine or system that involve sequencing of jobs in service facilities.

Replacement Models
These models deal with commuting replacement policy in situations when the need arise to replace a machine or its item parts. Replacement models help in case an equipment fails completely or instantaneously.

Simulation Models
The complex models that involve a number of variables and constrained relationships use simulation techniques to resolve a variety of problems.