Requirements Analysis

The main purpose of the requirements analysis is to analyze the gathered information to get a clear understanding of the product to be developed, with a view to removing all inconsistencies, incompleteness, and ambiguities from the initial customer perception of the problem. After the analyst has understood the exact customer requirements, he proceeds to identify and resolve the various problems that he detects in the gathered requirements.

There are three main types of problems in the requirements analysis that the analyst needs to identify and solve:

• Ambiguity: An anomaly is an ambiguity in the requirement. When a requirement is anomalous, several interpretations of that requirement are possible. Any anomaly in the requirements can lead to the development of incorrect systems since an anomalous requirement can be interpreted in several ways.
  
  The following is an example of anomalous requirements: For an institute office automation system, the office clerks mentioned that during the final grade computation, if any student scores a sufficiently low grade in a semester, then his parents should be informed. But, the clerk could not provide any well-defined criteria of what can be considered as a ‘sufficiently low grade’.
  
  
• Inconsistency: Two requirements are said to be inconsistent if one of the requirements contradicts the other, or two end-users of the system give inconsistent information of the requirement.
  The following is an example of an inconsistent requirement: For an institute automation system, one of the clerks described that a student securing fail grades in three or more subjects should have to repeat the entire semester. Another clerk mentioned that there is no provision for any student to repeat a semester.
  
  
• Incompleteness: An incomplete set of requirements is one in which some requirements have been ignored. Often, the incompleteness is caused by the inability of the customer to visualize the system that is to be developed and to anticipate all the features that would be required.
  
  
  The following is an example of an incomplete requirement: For an institute automation system, suppose one of the clerks mentioned that if a student secures a grade point average of less than 6, then the parents of the student must be intimated about the regrettable performance through a postal letter and they should also be intimated by e-mail. However, on an examination of all other requirements, it was found that there is no provision by which either the postal or e-mail address of the parents of the students can be entered into the system. The feature that would allow entering the e-mail and postal address of the parents of the students is missing, making the requirements incomplete.