Chapter 8 analysis interviewing & using DFD.pptx

Chapter 8 system analysis and design

1. Course: CSC1108 - System Analysis & Design Semester: January 2024 Lecturer: Ms Jayashiry Morgan

2. Chapter 8: Analysis Interviewing & Using Data Flow Diagram

3. Learning Outcome By the end of this session, students should be able to explain: How does interviewing works for analysis phase? How to choose the right interview questions? Analyze DFD Create DFD

4. Objective Understanding the core of systems analysis - information collection

5. Traditional Methods for Gathering Requirements Interviews : Directly engaging with users, managers, shareholders, etc., to gather insights about existing systems and improvement suggestions. Group Interviews : Collaborative discussions with multiple stakeholders to obtain a broader perspective. Nominal Group Technique : A structured approach for group discussions, ensuring equal participation and idea generation. Direct Observation : Actively observing system users and processes to gain firsthand insights. Document Collection : Gathering relevant paperwork, including procedures, forms, and reports, to comprehend the current system and organizational operations.

6. Analysis: Interviewing Interviewing and Listening Interviewing Groups

7. Interview Preparation Schedule convenient interview times. Explain the general nature of the interview to participants in advance. Encourage participants to think about specific questions or issues. Prepare questions and anticipate possible responses. Create an interview guide or checklist for a structured approach.

8. Choosing Interview Questions Decide on the mix of open-ended and closed-ended questions. Open-ended questions encourage free discussion and in-depth responses. Closed-ended questions provide specific answer options, suitable for well-known information.

9. Interview Guidelines Avoid phrasing questions that imply right or wrong answers. Listen attentively to verbal and non-verbal cues during the interview. Record the interview (with permission) or take detailed notes. Type up notes within 48 hours, separating facts from interpretations. Clarify unclear points with follow-up questions and verify notes' accuracy. Send a written copy of notes to the interviewee as a courtesy. Express gratitude for the interviewee's time.

10. Setting Expectations Avoid setting expectations about the new system unless confirmed. Emphasize the iterative nature of systems development and the consideration of multiple perspectives.

11. Diverse Perspectives Seek input from various stakeholders, including potential users, managers, and IT staff. Understand different perspectives to make informed recommendations or design decisions.

12. Group Interviewing and Nominal Group Technique (NGT)

13. Challenges of Individual Interviews Reconciliation of contradictory information may be time-consuming. Follow-up calls and additional interviews might be necessary. Efficient information gathering becomes challenging.

14. Group Interviews Conducted with multiple key individuals simultaneously. More effective use of time compared to individual interviews. Allows participants to hear diverse opinions and engage in discussions. Synergies often occur, revealing additional insights. Scheduling can be a challenge, especially with a larger group.

15. Nominal Group Technique (NGT) Group members work alone initially, generating individual ideas. Facilitator guides the pooling of ideas, ensuring each member contributes. Discussion and clarification of each idea take place. Facilitator and group work together to prioritize and refine ideas. Applied in requirements determination to identify system problems or new features. NGT complements group interviews, enhancing idea generation and prioritization.

16. Data Flow Diagramming

17. Versatility of DFDs Represent both physical and logical information systems. Effective for depicting data flows in both physical and logical contexts. Distinguishable from flowcharts in terms of orientation (physical vs. logical).

18. Symbol Definitions Data Flow : Represents data in motion, moving within the system. Data Store : Represents data at rest, regardless of physical location. Process : Signifies the work or action performed on data for transformation, storage, or distribution. Source/Sink (External Entity) : Origin and/or destination of data, located outside the system.

19. Standard Sets of Symbols Two standard sets ( Gane and Sarson, DeMarco and Yourdon). Symbols include arrows for data flows, rectangles for processes (rounded corners in Gane and Sarson), squares for source/sinks, and rectangles with a missing side for data stores (two parallel lines in DeMarco and Yourdon).

20. Comparison of DeMarco and Yourdon with Gane and Sarson DFD symbol sets Textbook page 206

21. Source/Sink Clarification Always external to the information system, defining system boundaries. Represents entities outside the system, such as organizations, individuals, or other information systems. Not concerned with internal processing within the source/sink. Emphasizes data movement through the system rather than physical location.

22. DFD EXAMPLE - DFD of Food Ordering System Textbook page 209

23. Data Flow Diagramming Rules 1. Process: No process can have only outputs; it must also have inputs. Otherwise, it would create data miraculously. Similarly, no process can have only inputs; it must have outputs. Otherwise, it would be a data sink. Processes are labeled with a verb phrase.

24. Data Flow Diagramming Rules 2 . Data Store: Data cannot move directly from one data store to another; it must go through a process. Data cannot move directly from an external source to a data store; it must go through a process. Data cannot move directly from a data store to an external sink; it must go through a process. Data stores are labeled with a noun phrase.

25. Data Flow Diagramming Rules 3. Source/Sink: Data cannot move directly from a source to a sink; it must go through a process if relevant to the system. Source/sinks are labeled with a noun phrase.

26. Data Flow Diagramming Rules 4. Data Flow: A data flow has only one direction of flow between symbols. A fork indicates the same data going to different locations. A join indicates the same data coming from different locations. A data flow cannot go directly back to the same process; it must involve at least one other process. Data flow to a data store implies update (delete or change). Data flow from a data store implies retrieval or use. Data flows are labeled with a noun phrase; multiple noun phrases can appear on a single arrow if they move together.

27. Rules Textbook page 212

28. Using DFDs as Analysis Tools Detecting Discrepancies Addressing Procedural Redundancies Identifying Inefficiencies Comparing Current and New Logical Systems Informing Design Decisions

29. CLASS ACTIVITY Each group will be given 5 rules of data flow diagramming. Create slide for each rule to explain the rule, together with an example. (1 slide = 1 rule) Present to the class. Group 1: A, B, D, E, F Group 2: H, J, K, L, M