Top-down analysis and design: how does the level of detail typically change across successive phases in this approach?

Introduction / Context:
Top-down analysis and design is a cornerstone of structured methods. The idea is to start from a high-level view of the problem or system and iteratively refine it into lower-level components until every function, interface, and rule is specified precisely enough for implementation and testing. Understanding how detail evolves across phases is essential for planning deliverables and review gates.

Given Data / Assumptions:

• The approach begins with a broad, abstract specification (context diagrams, major functions).
• Each subsequent phase decomposes earlier elements into finer-grained parts.
• The goal is progressive elaboration until modules and procedures are well defined.

Concept / Approach:
Top-down refinement follows a hierarchy: system → subsystems → modules → components → procedures. With each step, descriptions become more detailed and closer to executable specifications. This enables better control of complexity, clearer interfaces, and easier validation at each level of abstraction. Bottom-up design does the reverse; agile and iterative frameworks may mix both, but in classic top-down, increasing detail per phase is the rule.

Step-by-Step Solution:

Verification / Alternative check:
Structured design texts depict DFD leveling (context → level-0 → level-1) and module refinement, each adding detail and specificity. Reviews at each level confirm completeness and consistency.

Why Other Options Are Wrong:

• Same detail: contradicts the idea of progressive elaboration.
• Less detail: would represent abstraction—not refinement.
• All/None: incompatible with the core definition of top-down refinement.

Common Pitfalls:
Assuming documentation volume equals detail; detail means specificity and granularity of definitions, not only page count.

Final Answer:
each succeeding phase is more detailed than the phase before it