Comparison of SDLC Models
Summary Comparison Table
| Model | Requirements | Flexibility | Risk Handling | Cost | Best For |
|---|---|---|---|---|---|
| Code-and-Fix | Not needed | Very high (no structure) | None | Low upfront, high long-term | Tiny scripts, prototypes |
| Waterfall | Fixed, clear | Very low | Poor (late detection) | Predictable | Small/medium, stable requirements |
| Evolutionary | Evolving | High | Moderate | Variable | Unclear/evolving requirements |
| Incremental | Known, divisible | Moderate | Moderate | Higher than Waterfall | Early delivery of core features needed |
| Prototyping | Unclear/vague | High | Moderate | Extra prototype cost | UI-heavy, unclear requirements |
| Spiral | Can evolve | High | Excellent (dedicated risk phase) | High (many iterations) | Large, high-risk, complex projects |
| RUP | Use-case driven | High | Good | Moderate-High | Large, iterative OO projects |
| RAD | Known, time-boxed | Moderate | Low | Low, fast | Small-medium, tight deadline |
| Agile | Very flexible | Very high | Continuous (each sprint) | Variable | Fast-changing requirements, close customer collaboration |
Key Comparison Dimensions (how to evaluate any model)
- How well-defined are requirements upfront?
- How much customer involvement is needed throughout?
- How is risk managed?
- How early is working software delivered?
- How much documentation is produced?
- How well does it handle changing requirements?
General Trend
Models have evolved from rigid & sequential (Waterfall) → iterative & risk-aware (Spiral, RUP) → flexible & customer-centric (Agile), reflecting the industry's response to the software crisis and changing project needs.
Exam tip: A common question is "Compare Waterfall, Spiral, and Agile models." Use the 6 comparison dimensions above as your answer structure — examiners want structured comparison, not just definitions.