Data flow diagrams represent the logical flow of data within the system. DFD do notexplain how the processes convert the input data into output. They do not explain how the processing takes place.DFD uses few symbols like circles and rectangles connected by arrows to represent dataflows. DFD can easily illustrate relationships among data, flows, external entities stores.DFD can also be drawn in increasing levels of detail, starting with a summary high levelview and proceeding o more detailed lower level views.Rounded rectangles represent processes that transform flow of data or work to be done.Rectangle represents external agents- the boundary of the system. It is source or destination of data.
•Choose meaningful names for the symbols on the diagram.
• Number the processes consistently. The numbers do not imply the sequence.
•Avoid over complex DFD.
•Make sure the diagrams are balanced
The data dictionary is used to create and store definitions of data, location, format for storage and other characteristics. The data dictionary can be used to retrieve the definitionof data that has already been used in an application. The data dictionary also stores someof the description of data structures, such as entities, attributes and relationships. It canalso have software to update itself and to produce reports on its contents and to answer some of the queries.
Determining the Information Requirement
The sole purpose of the MIS is to produce such information which will reduceuncertainty risk in a given situation.
The difficulty to determine a correct and complete set of information is on account of thefactors given below:1. The capability constraint of the human being as an information processor, a problemsolver and a decision-maker.2. The nature and the variety of information in precise terms.3. Reluctance of decision-makers to spell out the information for the political and the behavioural reasons.4. The ability of the decision-makers to specify the information.In spite of these difficulties, methods are evolved based on the uncertainty scale, startingfrom the low to the high level of uncertainty. If the uncertainty is low, seekinginformation requirement or needs is easy as against a very high level of uncertainty.
Asking or Interviewing
In this method a designer of the MIS puts questions or converses with the user of theinformation and determines the information requirements. Putting the questions is an artand it should be used properly to seek information.When the user has to select one answer from a finite set of answers a closed questionshould be asked. For example, "Which are the raw materials used for making a product?"But an open question is put, when the user has no precise knowledge but has an ability todetermine all answers to select one out of them?
Determining from the Existing System
In a number of cases the existing system, which has been evolved after a number of years, and has been designed out of experience gives straightaway the requirement of information. In any situations, systems from other companies can give additionalinformation requirements.The fund of knowledge is available from the textbooks, handbooks, research studieswhich can determine the information requirement.
Analyzing the Critical Success Factors
Every business organization performs successfully on efficient management of certaincritical success factors. Other factors are important and play a support role in thefunctioning of the organization. Many times a function is singularly critical to thesuccessful functioning of a business organization.For example, in a high technology business, the management of the technology becomesthe critical function. Or in a service organization, the management of service becomes acritical...