The relative merits and drawbacks of different methodologies and when they might be used

1.2.3 Software Development

Software Development — Note 2 of 3

Candidates need to understand the tasks, processes, benefits and drawbacks of each model and the similarities and differences between each. They need to understand where each model is most suitable to use, and be able to justify the use in a situation.

What you need to know

No methodology is best for every project. You need to compare the merits and drawbacks of each methodology and recommend one for a given scenario, justifying your choice by referring to the project's size, risk, clarity of requirements and how involved the client can be.

What to know

Waterfall merits: simple to manage, clear stages and documentation, easy to measure progress. Drawbacks: hard to change requirements once a stage is complete; users see the product late. Suits: small or well-understood projects with fixed, clear requirements.
Agile merits: adapts to changing requirements, frequent working versions, regular user feedback. Drawbacks: less documentation; needs the client to be available; hard to predict total cost and time. Suits: projects with unclear or changing requirements.
XP merits: very high code quality; pair programming spreads knowledge; tests are written first. Drawbacks: pair programming is costly; needs a customer representative on the team; less focus on design and documentation. Suits: small teams where quality is critical and requirements change.
Spiral merits: risks are identified and dealt with early; suits very large, complex projects. Drawbacks: expensive, needs risk assessment expertise, can be slow. Suits: large, high-risk or high-budget projects.
RAD merits: users are involved throughout, so the final product matches their needs; working prototypes produced quickly. Drawbacks: poor for very large or complex systems; needs continual user involvement; code quality can suffer. Suits: small to medium projects where the user interface matters and requirements are unclear.

Exam technique

Tip:In extended answers, compare at least two methodologies and finish with a justified recommendation linked to the scenario.
Mistake:Writing generic advantages without linking them to the project described.