Development Methodologies

According to CMS (2008), "A system development methodology refers to the framework that is used to structure, plan, and control the process of developing an information system.". Some of the system development methodologies include Waterfall method, Prototyping, Incremental, Spiral and RAD.

Waterfall method (Linear framework)

Some advantages of the model is that its easy for understanding  easy to manage, and phases are completed one at a time. A weakness in this model is that it's costs, slow and it is hard to respond to a change and any changes that occur later are costly (CMS, 2008). The five phases of the waterfall model in sequential order:

• Requirements specification
• Design
• Implementation
• Integration
• Testing
• Installation
• Maintenance

In this methodology the project is divided into phases one after the other with some overlap and splash back acceptable between phases. The stages in this method are feasibility study, system investigation, system analysis, system design, implementation, review and maintenance. A positive point of that waterfall method is easy for planning, conserves the resources and the progress is measurable. As stated by Deeb (2010), it allows for  departmentalization and managerial control.

Spiral methodology (Combination linear and iterative framework)

According to the research done by Deeb (2010), The spiral model was developed by Dr. Barry Boehm and is an "enhancement of the waterfall mode with risk analysis preceding each phase of the cascade". It is used in large systems for internal development and effective when software are reused. Like the waterfall method, spiral methodology adds feedback to previous stages. 

Based on research by Chapman (2004), "The spiral methodology reflects the relationship of tasks with rapid prototyping, increased parallelism, and concurrency in design and build activities. The spiral method should still be planned methodically, with tasks and deliverables identified for each step in the spiral." 

How to select the best suited life cycle
The waterfall cycle is chosen if the user is aware of the requirements and it they are fixed. The spiral method is selected if there are possible risks in each phase and if the client wants to be aware of the decisions made in the phases.

Categories of methodologies

1. Data oriented design - useful for systems that process a lot of data E.g Banking system
2. Function/process oriented design - to process intensive systems
3. OO Methods - usefull for object oriented programs
4. User oriented design
5. Hypertext methods
6. Web methods- WML
7. Instructional design methods
8. Hybrid methods

Referred books/websites  

[Online] Available from: http://istqbexamcertification.com/what-is-waterfall-model-advantages-disadvantages-and-when-to-use-it/

[Online] Available from: http://www.cms.gov/Research-Statistics-Data-and-Systems/CMS-Information-Technology/XLC/Downloads/SelectingDevelopmentApproach.pdf

[Online] Available from: http://cs.anu.edu.au/student/projects/10S1/Reports/Ahmad%20Deeb.pdf

[Online] Available from: http://www.hyperthot.com/pm_sdm.htm