Data Collection & Analysis
Before building any system, you must collect data about the current problem and analyse it to determine what the new system needs. This is the critical first stage of the SDLC.
Learning Objectives
- 11.2.1.3 Describe data collection methods
- 11.2.1.4 Apply data analysis techniques
- 11.2.1.5 Compare alternative solutions
Conceptual Anchor
The Doctor Analogy
A doctor doesn't prescribe medicine without first examining the patient. Similarly, a developer must examine the current system (collect data), understand the symptoms (analyse), and consider treatment options (compare solutions) before building anything.
Rules & Theory
Data Collection Methods
| Method | Description | Advantages | Disadvantages |
|---|---|---|---|
| Interview | Face-to-face questions with stakeholders | Detailed answers, follow-up possible | Time-consuming, biased answers |
| Questionnaire | Written survey distributed to many people | Quick, wide audience, quantitative | Low response rate, no follow-up |
| Observation | Watch users perform tasks in real time | See actual workflow, find hidden issues | Users may behave differently |
| Document Review | Examine existing forms, reports, manuals | Factual, no user bias | May be outdated |
| Focus Group | Group discussion with selected users | Multiple perspectives, rich data | Dominant voices may skew results |
Data Analysis Techniques
| Technique | Description |
|---|---|
| Identify inputs/outputs | What data goes in? What comes out? |
| Identify processes | What transformations happen to the data? |
| Identify data stores | Where is data stored? Files, databases? |
| Identify constraints | Budget, time, hardware, legal requirements |
| Create DFDs | Visual diagrams showing data flow through the system |
Comparing Alternative Solutions
| Criterion | Questions to Ask |
|---|---|
| Technical feasibility | Can we build it with available technology? |
| Economic feasibility | Can we afford it? Will benefits outweigh costs? |
| Operational feasibility | Will users accept and use it? |
| Time feasibility | Can it be completed within the deadline? |
Open vs Closed Questions
Open: "How do you process student grades?" (detailed answer). Closed: "Do you use a spreadsheet? Yes/No" (quick, countable answer). Good questionnaires use both types.
Common Pitfalls
Skipping Data Collection
Building a system without proper data collection leads to a product that doesn't meet user needs. The most common reason software projects fail is poor requirements gathering.
Tasks
Name 5 data collection methods.
A school wants a new library system. Design a questionnaire with 5 questions (mix of open and closed) for librarians.
Compare building a custom system vs buying existing software for a small business. Use feasibility criteria.
Self-Check Quiz
Q1: Name 3 data collection methods and a disadvantage of each.
Q2: What are the 4 types of feasibility?