Comparing Staged and Iterative Processes

In this lesson, you'll explore the differences between staged and iterative design processes in software development. You'll recap the basics of each, compare them across key aspects with examples, and summarise the findings in a clear table for reference.

Learning Goals Learning Outcomes Teacher Notes

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1 Introduction
2 Overview of Staged and Iterative Processes
3 Comparing Structure
4 Comparing Flexibility
5 Comparing Risk Management
6 Comparing Delivery
7 Comparing Suitable For
8 Overall Comparison
9 Wrap Up
Quiz

1 - Introduction

In this lesson, you'll compare staged and iterative design processes in software development Here's what we'll cover:

Recap the basics of staged (waterfall) and iterative models.
Compare the two processes across key aspects, using examples to highlight differences.
Summarise the comparisons in a table for a clear overview.

2 - Overview of Staged and Iterative Processes

Before diving into comparisons, let's quickly recap the two processes you've learned about.

Staged Design (Waterfall Model): A linear approach where development flows sequentially through phases like requirements, design, implementation, testing, deployment, and maintenance. Each phase must be completed before the next begins.

Iterative Design: A cyclical approach where development is broken into small iterations or cycles. Each iteration involves planning, designing, implementing, testing, and reviewing a portion of the software, allowing for refinements based on feedback.

Think of staged as a straight line from start to finish, like a waterfall, and iterative as a loop that builds and improves gradually, like spiralling upwards.

3 - Comparing Structure

Let's compare the structure of staged and iterative processes.

Staged: Highly structured with fixed, sequential phases. Progress is linear, with clear milestones and documentation at each stage. It's easy to plan and track but rigid.
Iterative: Flexible structure based on repeating cycles or iterations. Each iteration produces a working prototype, allowing for incremental building. It's more adaptive but can seem less organised without strict phases.

Example: In staged, you fully design before coding; in iterative, you design a small part, code it, test it, then repeat for the next part.

Staged suits projects needing predictability, while iterative allows evolving structure.

4 - Comparing Flexibility

Now, consider flexibility in handling changes.

Staged: Low flexibility. Changes after a phase require going back, which is costly and time-consuming. Best for projects with stable requirements.
Iterative: High flexibility. Feedback from each iteration allows adjustments easily. Ideal for projects where requirements may evolve or user input is ongoing.

Example: If a client changes a feature midway, staged might delay the whole project; iterative can incorporate it in the next cycle.

Choose iterative for dynamic environments, staged for fixed scopes.

5 - Comparing Risk Management

Examine how each process manages risks.

Staged: Risks are identified early but addressed late. Issues found in testing might require major rework, increasing risk if assumptions are wrong.
Iterative: Risks are managed continuously. Each iteration tests assumptions early, reducing big surprises. Feedback loops help mitigate risks incrementally.

Example: In staged, a design flaw might only appear after implementation; in iterative, it's caught and fixed in early cycles.

Iterative spreads risk, while staged concentrates it at the end.

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Comparing Staged and Iterative Processes