Incremental Model (2017)

CSS CS Optional — Paper-I, Section-B, Topic V.

🔑 Definition

• System built as series of increments/"builds" — each adds functional capability.
• First increment = core product with basic requirements.

📌 How Each Increment Runs

• Mini-Waterfall per increment: analysis → design → code → test → deliver, repeated.

📌 Advantages

• Fast working software
• Early increments = usable, testable products
• Cheaper to accommodate scope changes
• Easier to test/debug (smaller pieces)
• Customer feedback on one increment steers the next

📌 Disadvantages

• Needs solid upfront planning + well-defined architecture
• Total cost can exceed Waterfall if increments aren't planned well

⚠️ MCQ Trap

• Incremental = complete, working slices added one after another.
• Evolutionary = keeps refining ONE evolving version.

📜 Past-Paper Questions & MCQs (CSS 2016–2026)

2018 · Paper-I · Q7(d) · 4 marks

Q. What type of project is not suited to incremental methods?

Ans.

• Small projects with few features, where splitting into increments only adds overhead.
• Projects with fixed, complete requirements and one final delivery, where waterfall is simpler.
• Systems that cannot be divided into independent parts, such as tightly integrated embedded or real-time control systems.
• Safety-critical systems (aircraft control, medical devices) that need a complete specification and full verification before any release.
• Projects with no stable overall architecture at the start, because later increments may force costly redesign.

Related

• The 2017 Q4(a) answer on choosing evolutionary versus incremental models is on Evolutionary Model (2017).