Short, brief note...

System analysis and design

• a six-phase problem-solving procedure for examining and improving an information system
• make up the systems life cycle

http://www.google.com.my/imglandingq=system+life+cycle&hl=en&sa=X&tbm=isch&tbnid=9e2wkzFCjuH73M:&imgrefurl=http://www.computing2008.com/dvd:analysis&imgurl=http://www.computing2008.com/computing2008/_media/dvd:141a.jpg%253Fw%253D%2526h%253D%2526cache%253Dcache&ei=nZKQTdeKJIq4vgO0kpCoDQ&zoom=1&w=252&h=247&iact=hc&oei=kJKQTau6JdC9ceXF9ZYK&page=3&tbnh=135&tbnw=138&start=37&ndsp=19&ved=1t:429,r:0,s:37&biw=1366&bih=624


Phase 1 : Preliminary investigation

• determine the need for a new information system
• concerned with three tasks : define the problem, suggest alternative solutions and prepare a short report
• accomplish by interviewing and making observations
• if information system is large, the survey is done by systems analyst
• if information system is small, the survey can done by end user
• report may include schedules for further development of the project and presented to higher management

Phase 2 : Systems analysis

• data is collected about the present system
• new requirements are determined for a new system
• concerned with gathering and analyzing data
• completed by documenting the analysis in report
• organization chart : shows levels of management and formal lines of authority
• systems analysis report : describes the current information system, the requirements for a new system,and a possible development schedule

http://www.google.com.my/imglandingq=system+design+in+system+life+cycle&hl=en&biw=1366&bih=624&tbm=isch&tbnid=zdd8ixYJ5hBvM:&imgrefurl=http://www.cs.uct.ac.za/mit_notes_devel/SE/Jul2006/html/ch02s04.html&imgurl=http://www.cs.uct.ac.za/mit_notes_devel/SE/Jul2006/html/images/02_005.png&ei=156QTYe4D467ce-drJIK&zoom=1&w=736&h=409


Phase 3 : Systems design 

• consists of three tasks : design alternative systems, select the best system and write a systems design report
• evaluate the alternative system for economic,technical and operational feasibility
• system design report is prepared for higher management and describes the alternative designs

Phase 4 : Systems development

• has three steps : acquiring software, acquiring hardware and testing the new system
• application software can be purchased as off-the-shelf packaged software and possibly modified, or it can be custom designed
• suggests that an electronic mailbox be installed for maintaining security
• the processed information is evaluated to see whether results are correct

Phase 5 : Systems implementation

• another name is conversion
• process of changing from old system to the new one and training people to use the new system
• four approaches to conversion : direct, parallel, pilot and phased
• direct approach : abandon the old, very risky, not recommended
• parallel approach : run old and new side by side, very low risky, however very expensive, not generally recommended
• pilot approach : convert part of organization first, less expensive but riskier than parallel conversion, recommended for situations with many people performing similar operations
• phased approach : implement gradually, less risky but more expensive than parallel conversion, recommended for situations with many people performing different operations

Phase 6 : Systems maintenance

• ongoing activity
• spend more time and money on this phase 
• has two parts : a systems audit and a periodic evaluation
• in systems audit, the system's performance is compared to original design specifications 
• to determine whether the new procedures are actually furthering productivity
• all systems are evaluated from time to time to determine whether they are meeting goals

Reference :
computing essentials 2011