LESSON 6 - Requirements Discovery

• Requirements discovery


  discovery the process and techniques used by systems analysts to identify or extract system problems and solution requirements from the user community.
• System requirement


  something that the information system must do or a property that it must have.

  Also called a business requirement.
• PIECES Classification of System Requirements

  1. Performance
  2. Information
  3. Economy
  4. Control (and security)
  5. Efficiency
  6. Service
• Performace requirements 


  represent the performance the system is required to exhibit to meet the needs of users
• Information requirement 


  represent the information that is pertinent to the users in terms of content, timeliness, accuracy, and format
• Economy requirements


  represent the need for the system to reduce costs or increase profits
• Control requirement


  represent the environment in which the system must operate, as well as the type and degree of security that must be provided
• Efficiency requiements 


  represent the system's ability to produce outputs with minimal waste
• Service requirements 


  represent needs in order for the system to be reliable , flexible, and expandable
• Results of Incorrect Requirements

  • The system may cost more than projected.
  • The system may be delivered later than promised.
  • The system may not meet the users’ expectations and that dissatisfaction may cause them not to use it.
  • Once in production, the costs of maintaining and enhancing the system may be excessively high.
  • The system may be unreliable and prone to errors and downtime.
  • The reputation of the IT staff on the team is tarnished because any failure, regardless of who is at fault, will be perceived as a mistake by the team.
• Consistent


  requirements are not conflicting or ambiguous.
• Complete


  requirements describe all possible system inputs and responses.
• Feasible


  requirements can be satisfied based on the available

  resources and constraints.
• Required


  requirements are truly needed and fulfill the purpose of the system.
• Accurate


  requirements are stated correctly.
• Traceable


  requirements directly map to the functions and features of the system.
• Verifiable


  requirements are defined so they can be demonstrated during testing.
• The Process of Requirements Discovery

  • Problem discovery and analysis
  • Requirements discovery
  • Documenting and analyzing requirements
  • Requirements management
• Ishikawa Diagram (Problem Discovery and Analysis)


  is a graphical tool used to identify, explore, and depict problems and the causes and effects of those problems.

  It is often referred to as a cause-and-effect diagram or a fishbone diagram.
• Fact-finding


  the formal process of using research, meetings, interviews, questionnaires, sampling, and other techniques to collect information about system problems, requirements, and preferences. It is also called information gathering or data collection.

  
  

  often brings systems analysts into contact with sensitive information.
• Fact-finding includes:

  • Company plans
  • Employee salaries or medical history
  • Customer credit card, social security, or other information
• Ethical behavior includes:

  • Systems analysts must not misuse that information.
  • Systems analysts must protect that information from people who would misuse it.
• Otherwise:

  • Systems analyst loses respect, credibility, and confidence of users and management, impairing ability to do job
  • Organization and systems analyst could have legal liability
  • Systems analyst could lose job
• Seven Fact-Finding Methods

  1. Sampling of existing documentation, forms, and databases.
  2. Research and site visits.
  3. Observation of the work environment.
  4. Questionnaires.
  5. Interviews.
  6. Prototyping.
  7. Joint requirements planning (JRP).
• Documenting the draft requirements with various tools:

  • Use cases
  • Decision tables
  • Requirements tables
• Analyzing requirements to resolve problems of:

  • Missing requirements
  • Conflicting requirements
  • Infeasible requirements
  • Overlapping requirements
  • Ambiguous requirements
• Formalizing requirements

  • Requirements definition document
  • Communicated to stakeholders or steering body
• Requirements management


  the process of managing change to the requirements.
• Sampling


  the process of collecting a representative sample of documents, forms, and records.
• Why to Sample Completed Rather than Blank Forms?

  • Can determine the type of data going into each blank
  • Can determine the size of data going into each blank
  • Can determine which blanks are not used or not always used
  • Can see data relationships
• Sampling Techniques

  1. Randomization
  2. Stratification
• Randomization


  a sampling technique characterized by having no predetermined pattern or plan for selecting sample data.
• Stratification


  a systematic sampling technique that attempts to reduce the variance of the estimates by spreading out the sampling—for example, choosing documents or records by formula—and by avoiding very high or low estimates.
• Observation


  a fact-finding technique wherein the systems analyst either participates in or watches a person perform activities to learn about the system.
• Work sampling


  a fact-finding technique that involves a large number of observations taken at random intervals.
• Questionnaire


  a special-purpose document that allows the analyst to collect information and opinions from respondents.
• Free-format questionnaire


  a questionnaire designed to offer the respondent greater latitude in the answer. A question is asked, and the respondent records the answer in the space provided after the question.
• Fixed-format questionnaire


  a questionnaire containing questions that require selecting an answer from predefined available responses.
• Types of Fixed-Format Questions

  1. Multiple-choice questions
  2. Rating questions
  3. Ranking questions
• Interview


  a fact-finding technique whereby the systems analysts collect information from individuals through face-to-face interaction.

  Can be used to: Find facts, verify facts, clarify facts, generate enthusiasm, get the end-user involved, identify requirement, solicit ideas and opinions