📚 IGCSE ICT (0417) Study Notes: The Systems Life Cycle – Implementation (7.4)

Hello future ICT expert! This chapter is all about the crucial moment when all your hard work pays off: System Implementation. This is where the shiny new system you designed and tested finally replaces the old one.
Don't worry, we'll break down the four main methods businesses use, looking at the pros and cons of each. Understanding risk management here is key!

1. What is System Implementation?

System Implementation is the process of putting the new ICT system into actual use. It follows the development and testing phases. It involves installing hardware, loading software, moving data, and most importantly, training the users.

This step is critical because no matter how good your design is, if the implementation goes wrong, the whole project can fail. Businesses must choose the safest and most effective method for their situation.

Think of it like moving house: You have to decide if you move everything at once (high risk!) or slowly, room by room (lower risk).

Quick Review: Prerequisite Steps
  • Before implementation, the system must have gone through rigorous Testing (7.3).
  • Staff must be trained on how to use the new hardware and software.

2. The Four Methods of Implementation

There are four core strategies a company can use to switch from the old system to the new one. They each represent a different level of risk and cost.

💡 Memory Aid: A simple way to remember the four P's and D: Dogs Play Pretty Peacefully (Direct, Parallel, Pilot, Phased).

2.1 Direct Changeover (The High-Risk Plunge)

Characteristics and Use:
This is the simplest and most dramatic method. The old system is stopped immediately, and the new system is started immediately.

Example: A small shop switches off its old cash registers on Sunday night and starts using the completely new computerised Point of Sale system on Monday morning.

✔ Advantages of Direct Changeover:
  • Fastest: The quickest way to get the new system running.
  • Cheapest: Only requires resources for one system (the new one).
❌ Disadvantages of Direct Changeover:
  • Highest Risk: If the new system fails, there is no backup. The company cannot operate.
  • Stressful: High pressure on staff and technical support from day one.
2.2 Parallel Running (The Safety Net)

Characteristics and Use:
For a set period, the old system and the new system run simultaneously. Both systems process the same data, and their outputs are compared.

Example: A payroll department calculates wages using their old spreadsheet system while simultaneously entering and calculating the same data using the new HR database system. They compare results to ensure the new system is accurate.

✔ Advantages of Parallel Running:
  • Lowest Risk: If the new system fails, the old system is still running as a reliable backup (a safety net).
  • Verification: Outputs can be easily compared, proving the new system is accurate before the old one is shut down.
❌ Disadvantages of Parallel Running:
  • Most Expensive: You are paying for maintenance and running costs for two systems.
  • High Workload: Staff have to input data and perform tasks twice, increasing stress and potential for human error in data entry.
2.3 Pilot Running (The Test Group Rollout)

Characteristics and Use:
The new system is used by a small, selected group or single branch of the organisation first. Once the pilot group confirms the system works without major flaws, it is then implemented across the entire organisation.

Example: A chain of 50 supermarkets implements its new inventory system only in the three Manchester branches first.

✔ Advantages of Pilot Running:
  • Contained Risk: If the system fails, only one small area is affected. The rest of the business continues to operate normally.
  • Focused Training: Staff training can be done gradually and focused on the small pilot group first.
  • Real-World Feedback: Developers get vital feedback from real users in a real work environment.
❌ Disadvantages of Pilot Running:
  • Slow: Takes longer than direct changeover to roll out to the whole company.
  • Lack of Scaling: Issues that occur when running the system on a massive scale might not be spotted in the small pilot run.
2.4 Phased Implementation (The Step-by-Step Approach)

Characteristics and Use:
The new system is introduced in stages, module by module, or function by function, across the entire organisation.

Example: A new accounting system is implemented in phases: Phase 1 replaces the old ledger system; Phase 2 replaces the old invoicing system; Phase 3 replaces the old stock ordering system.

✔ Advantages of Phased Implementation:
  • Manageable: The scale of change is easier for users to manage, as they only learn one new module at a time.
  • Errors Contained: If one module has a fault, it doesn't shut down the entire system or affect other functions.
❌ Disadvantages of Phased Implementation:
  • Time-Consuming: This is generally the longest method of implementation.
  • Compatibility Issues: You need to ensure the new modules are compatible with the existing (old) modules still being used.

3. Implementation Method Summary: Choosing the Right Strategy

Choosing the best implementation method depends entirely on the nature of the business and the level of risk they are willing to accept.

High Risk vs. High Cost:

  • If the system is low-risk (like a new email client) or needs to be operational immediately, Direct Changeover might be chosen.
  • If the system is mission-critical (like banking transactions or patient records), Parallel Running provides the necessary safety net, despite the high cost.

⭐ Quick Review Box: Implementation Methods

Method: Direct Changeover
Risk Level: Highest
Key Feature: Old system off, new system on (instant switch).

Method: Parallel Running
Risk Level: Lowest
Key Feature: Both run together (safety net), double the workload.

Method: Pilot Running
Risk Level: Medium/Low (Risk is contained)
Key Feature: Tested in one department/branch first.

Method: Phased Implementation
Risk Level: Medium (Slow rollout)
Key Feature: Introduced module-by-module across the organisation.


You have successfully implemented your knowledge of implementation methods! Remember the risks and rewards of each one – examiners often ask you to justify why one method is better than another in a given scenario.