System Analysis Flashcards
5 stages of Feasibility
Technical
Economic
Legal
Organisational
Schedule
Methods of Analysis
Interviews
Questionnaires
Examining current system documentation
Observing current users
Study the existing system documentation
Benefits: Team can see how the current system ‘should’ be operating, inexpensive method of gathering lots of information fairly quickly, can identify storage requirements.
Drawbacks: Staff may not be following procedures in the documentation and may be using the system in their own way, documentation may be out of date and
not updated to reflect system change.
Carry out a questionnaire of staff
Benefits: Relatively cheap to produce for a large number of people, can be distributed worldwide, could be completed online so results, can be available very quickly, gather a large number of responses in a short time.
Drawbacks: Have to be designed by experts or information could be unusable, limited responses, people are ‘too busy’ and may not complete or give correct answers.
Interview staff / focus groups
Benefits: Can gather large amount of detailed information, can make judgements on validity of information from personal contact or body language, can ask ‘follow up’ or ‘open ended’ questions to gather more detailed information in selected areas
Drawbacks: Time consuming and expensive to carry out, has to be carried out by trained interviewer or closed questions written by experts, difficult to analyse large amount/wide variety of information, difficult to analyse wide variety of information.
Observe the current system in practice
Benefits: Can actually see what is really happening and do not have to rely on what people tell you what they think is happening
Drawbacks: Very time consuming and therefore expensive to carry out, staff may feel like they are being watched and therefore behave differently so do not actually see what goes on every day, cost of sending analysts around the world.
Designing algorithms
Algorithms must be well designed as this can effect the speed of a process such as searching and sorting
Designing Human Computer Interface
This involves the design of how the computer and human will interact with each other, involving hardware and software.
Designing data structures
Files and records must be designed
Direct Changeover
Meaning a complete changeover of everything in a single pass. This is appropriate for smaller systems or for organisations whose computers cannot work with the old and new systems simultaneously.
Pilot Changeover
In which a small group of users would use the new system before the bulk of the organisation changed over. Using this method, bugs can be resolved with minimal inconvenience.
Parallel changeovers:
Involve the old and new systems being available simultaneously. If any problems become evident on the new system, the old system still exists throughout the organisation.
Phased changeovers:
Typically happen one department at a time. Larger organisations or organisations undergoing significant change might select this method, as they would be more vulnerable to bugs.
Alpha testing
Is conducted by highly skilled developers, typically module by module, subroutine by subroutine.
Beta testing
Is conducted by prospective end users, who are regular users of the system as they would use the end product, notifying the developers of any bugs they identify.
Acceptance testing,
Conducted by the end users/prospective customers, answers the question ‘is this what we wanted?’ rather than ‘does this work?’.
Perfective maintenance
Aims to make a functioning system even better, perhaps by adding multiple input methods, speeding up a network connection or tweaking an interface.
Adaptive maintenance
Changes a system to match changing requirements. A new law might require storage of additional data or the rate of VAT might change.
generation file backup
This involves storage of three of the most recent versions of master file. Useful if one version is corrupted: the previous version(s) is still available. Data should be stored off site in case of a disaster.
Incremental Back up
Only backs up data that has changed since the last backup. Useful as it saves storage space and is faster than full backup. Only allows the user to restore the most recent backup.
Delta Change Back up
Backs up only parts of the file that have changed but only specific data within a file not the whole file like incremental. Focuses on the specific changes (deltas) made within a file reducing backup size further. Even more storage efficient than incremental as it only saves the changes within the file and not the entire file
User documentation
How software is to be installed and used; how to use any specialist hardware; basic troubleshooting instructions.
Maintenance documentation
Annotated Code listings – Code listings that abide by the coding standards set out by the development company. Normally self-documenting and/or annotated.
Variable lists – including names, data types, visibility and a description of purpose
Data dictionaries – listings of fields within each file, to include names, primary keys, data types and requirements for validation.
