Todays managers depend on information systems for decision making. The managers have handful of data around them but manually they cannot process the data accurately and with in the short period of time available to them due to heavy competition in modern world. Therefore mangers depend on information systems.

The concept of MIS:

Management: Management has been defined in a variety of ways, but for our purposes it comprises the process or activities what managers do in the operation of their organization: Plan, Organize, Initiate and Control operations.

Information:

Data are facts and figures that are not currently being used in a decision processes and usually take the form of historical records that are recorded and filed without immediate intent to retrieve for decision making.

Information consists of data that have been retrieved, processed or otherwise used for information or inference purposes, argument, or as a basis for  forecasting or decision making.

System can be described simply as a set of elements joined together for a common objective. A subsystem is is part of a larger system with which we are concerned. All systems are part of larger systems.

The objective of an MIS (Management Information System) is to provide information for decision making on planning, initiating, organizing, and controlling the operations of the subsystems of the form and to provide a synergetic organization in the process. 

Decision Support System: It is sometimes described as the next evolutionary step after Management Information Systems (MIS) . MIS support decision making in both structured and unstructured problem environments.. It supports decision making at all levels of the organization .IS (Information Systems) are intended to be woven into the fabric of the organizations , not standing alone. IS support all aspects of the decision making process.MIS are made of people, computers, procedures, databases, interactive query facilities and so on. They are intended to be evolutionary/adaptive and easy for people to use. 

Methods of Decision Making