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easyProject Manager interview question

What is the difference between agile and waterfall, and when would you use each?

What the interviewer wants to hear

  • Waterfall: sequential phases, detailed upfront plan
  • Agile: iterative, short cycles, frequent feedback
  • Waterfall suits stable requirements and fixed constraints
  • Agile suits uncertainty and changing requirements
  • Hybrid approaches are common

Model answer

Waterfall, or predictive, delivery moves through phases in order: requirements, design, build, test and deploy, with a detailed plan up front. It works well when requirements are clear and unlikely to change, such as building an office fit-out or a regulatory system with fixed rules. Agile delivery works in short cycles, like two-week sprints, delivering small working pieces and getting feedback often. It suits projects with uncertain or changing requirements, such as a new customer app. In practice many organisations use a hybrid. For example, a bank may plan budget, compliance milestones and infrastructure in a predictive way, while the software team delivers features in sprints. I choose the approach based on how stable the requirements are, the risks and how the organisation works.

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