1.2 Analysis
System Analysis: A series of steps in the process of investigating a problem, understanding user requirements with the aim of identifying how a new system will solve the problem.
Purpose of Analysis
Current System: Research how the current system works using fact finding.
Identify input, output and processes.
Describe the old system with DFD's.
Document findings.
Agree the DFD's with the end user.
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New system: Define requirements for the new system (Functional and non- functional).
Specify hardware and software.
Identify constraints.
Feasibility
What is a feasibility study?
A feasibility study is the preliminary investigation of a problem to decide if a solution is possible and how it may be done.
TELOSS
Technical
Economic
Legal
Operational
Schedule
Social
What aspects need to be investigated?
Problems: Unless the existing system problems are well understood, it would be impossible to design an appropriate solution
Organisation and Structure: The analyst must understand how the organisation is managed, who is responsible for the various aspects of the system
Inputs: The sources of information must be identified as they are likely to be the same in the new system. Every piece of data required by the system must be clearly identified as part of the investigation.
Processes: Verbs are used to describe processes. What happens as data passes through the system. How an input is used to update files and create and output.
Outputs: Every piece of data needs to be identified to see if it is necessary, accurate and efficiently produced.
Files: Analysts must understand; What files are there on the current system and why are they necessary. The contents of the files. How the files are maintained.
Fact Finding
Interviews
Users are asked on a one-to-one basis or in groups. The interview may be structured or unstructured and it allows for follow up questions to be asked.
Questionniares
Involves a representative group of users who complete a set of questions: The questions may be open or closed and are aimed at collecting detail of the current data and processes.
Observations
Users are shadowed by systems analyst as they perform a particular task or their everyday task. To identify what the role entails, the data required and the processes involved .
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