The systems life cycle
How a new ICT system is analysed, designed, developed and tested, implemented, documented and evaluated.
📌 Key points
- The stages of the systems life cycle are analysis, design, development and testing, implementation, documentation and evaluation.
- Methods of researching the current system: observation (first-hand and reliable, but people may work differently when watched), interviews (detailed and can follow up answers, but time-consuming), questionnaires (many people quickly and anonymously, but questions cannot be explained) and examining existing documents (shows the data used, but can take time).
- Analysis also identifies the inputs, outputs and processing of the current system, its problems, the user and information requirements, and the hardware and software needed.
- Design includes file and data structures (field names, data types, field lengths), input forms, output formats (screen layouts and reports), validation routines and verification methods.
- Validation checks: range, character (type), length, format, presence and check digit. Verification: visual check and double data entry.
- Testing uses a test plan with normal data (should be accepted), abnormal data (should be rejected) and extreme data (on the limits, should be accepted), and finally live data.
- Implementation methods: direct changeover (old system stops, new one starts at once: quick and cheap but risky), parallel running (both run together: safe but costly and double work), pilot running (one branch or department first) and phased implementation (one part of the system at a time).
- Technical documentation helps experts maintain and upgrade the system (e.g. program listings, flowcharts, file structures, hardware and software requirements, validation rules); user documentation helps users run the system (e.g. how to load, save and print, error messages and troubleshooting, FAQs).
- Evaluation compares the new system with the original requirements, uses feedback from users, and identifies limitations and improvements.
📖 Key terms
- Analysis
- The stage where the current system is studied and the requirements of the new system are identified.
- Direct changeover
- The old system is stopped and the new system is started immediately.
- Parallel running
- The old and new systems run side by side until the new one is trusted.
- Pilot running
- The new system is introduced in one branch or department first.
- Phased implementation
- The new system is introduced one part at a time.
- Technical documentation
- Documentation that helps programmers and analysts maintain and improve the system.
- User documentation
- Documentation that explains how to use the system.
✏️ Worked example
A hospital is replacing its patient records system. Recommend an implementation method and justify it.
- Choose parallel running (old and new systems run at the same time).
- Patient data is critical, so it must not be lost if the new system fails.
- If the new system has errors, the old system can still be used, so patient care is not affected.
- Outputs of both systems can be compared to check the new system is correct.
- The drawback is extra cost and staff time because data is entered twice, but this is worth it for safety.
For implementation methods, always link your choice to the scenario: critical data suggests parallel running; many branches suggests pilot; a small shop with a tight budget may suit direct changeover.
Test yourself8 questions from a bank of 15. A new mix every time.
Start the quiz →