11. System Analysis Flashcards
What is systems analysis?
The process of studying a procedure or business to identify a purpose and create a system which will efficiently achieve it.
What is a feasibility study?
Establishes whether a project can be done or not, given a scope. It considers whether the project is desirable for the developing company.
What is economic feasibility?
Considers whether the costs of everything can be covered, such as software licenses and hardware, and whether the profit will be worth it.
What is legal feasibility?
Projects have to comply to all the laws in all the countries in which the product will be released.
What is time feasibility?
Estimates how long it will take to complete a project and whether it can be completed within the required time frame (if there is one).
What is technical feasibility?
Considers whether a project can be done with the technology available e.g. accurate speech recognition is not possible and projects requiring this would not be technically feasible
What is political feasibility?
Evaluates whether the positives of a project outweigh the potential negative publicity.
What is investigation and analysis?
This stage aims to develop an understanding of how effective the current system is and to identify what needs to be altered/added. The investigation part involves gathering data about the current system, and the analysis part involves a systematic attempt to understand that data.
What is current documentation and what are the benefits and drawbacks?
When the current system documentation is studied.
adv:
- analyst can see how the system should be operating
- inexpensive method of gathering lots of data quickly
- can identify storage requirements
disadv:
- staff may not be following the procedures in the documentation
- documentation may be out of date
What are questionnaires and what are their benefits and drawbacks?
When questionnaires are carried out on staff.
adv:
- cheap to produce for a large number of people
- can be distributed worldwide
- could be completed online so results can be retrieved quickly
disadv:
- people may not answer truthfully
- have to be designed by experts or information may be unusable
- people might be too busy to complete
What are interviews and what are the benefits and drawbacks?
When staff are interviewed.
adv:
- can gather large amounts of detailed info
- can make judgements on validity of info from body language
- can ask follow up and open ended questions
disadv:
- time consuming and expensive
- has to be carried out by a trained interviewer
- difficult to analyse large, detailed info
What is observation and what are the benefits and drawbacks?
When the current system is observed in practice.
adv:
- can actually see what is really happening and you do not have to rely on what other people tell you
disadv:
- very time consuming and expensive
- staff may behave differently as they are being watched
What is the design stage in the system analysis process?
When the new system is represented and interpreted in appropriate diagrammatic form, such as with pseudocode or data flow diagrams. Suitable hardware and software is also selected at this stage.
What is involved in the program testing stage of the systems analysis process?
Test strategy: a document that sets out an approach to testing a software application
Test plan: a document that details the scope, approach, resources and schedule of intended test activities
Test data: data that is designed to ensure and correct outputs produced by the system
What are the types of test data?
Typical: data that is correct and should be processed correctly by the program
Erroneous: data that would cause the program to fail if not validated
Extreme: data that is correct but is at the extreme of a boundary of an acceptable range of values
What is the alpha testing method?
Alpha testing is conducted by the developers, module by module, subroutine by subroutine. It is conducted by highly skilled professional testers and requires a testing environment. Reliability and security testing are not performed in-depth during alpha testing.
What is the beta testing method?
Beta testing is conducted by prospective users, who use the system as they normally would and notify the developers of any bugs. It can be conducted by inexperienced end users and does not require a lab environment. Reliability, security and robustness are checked during this stage.
What is the acceptance testing method?
Acceptance testing is conducted by end users and aims to evaluate if the software is what the developers wanted, rather than if it works.
What is a direct changeover and what are its advantages and disadvantages?
A direct changeover is a sudden changeover to using a new system.
adv:
- cheaper to implement
- new system is available immediately
- can be least disruptive if implemented well
disadv:
- new system may not work as well until staff are used to it
- if new system fails, the organisation will have no system, which could be catastrophic
What is a parallel changeover and what are its advantages and disadvantages?
A pilot changeover is when both the old and new system are running together at the same time.
adv:
- if the new system fails, the old one can still be used
- new system is available immediately
- the outputs from the old and new system can be compared to check that the new system is running correctly
disadv:
- having two systems at the same time could cause confusion
- expensive as it would require staff to work longer in order to make use of both systems
What is a phased changeover and what are its advantages and disadvantages?
A phased changeover is when the old system is replaced by the new system bit by bit, one function at a time.
adv:
- allows users to gradually get used to the new system
- difficulties can be identified easier and therefore resolved easier
- staff training can be done in stages
disadv:
- slower to get new system up and running compared to other methods
- if part of the new system fails, there is no back up
- some systems cannot easily be broken down into functions
What is a pilot changeover and what are its advantages and disadvantages?
A phased changeover is when the old system is replaced by the new system part by part, one part of the organisation at a time.
adv:
- if something goes wrong with the new system, only part of the organisation is affected
- difficulties can be identified easier and therefore resolved easier
- staff who are already use to the system can help other staff who are new to the system
disadv:
- if the new system fails, there is no backup for the part of the organisation it is being tested on
- slower to get new system up and running
What is adaptive maintenance?
When a system is changed to meet the needs of users. Bugs can be fixed and extra functionality is added based on the needs of the users.
What is perfective maintenance?
Aims to make the system perfect by improving performance and fixing all bugs. This means that it must be tested perfectly as not all bugs will be found if there is a flaw in the test strategy.
What is corrective maintenance?
Aims to remove bugs that were not addressed during testing. Bugs are dealt with as they appear, and the original system is changed as little as possible.
What is user documentation and what does it contain?
A document aimed at instructing the user how to use software correctly. It contains:
- step by step guides on using the main features of the system
- installation guide
- license info
- reference manual
- online help such as input fields
- error messages and troubleshooting guides
- FAQs
- glossary
What is maintenance documentation and what does it contain?
A technical document produced to help future developers understand and maintain the system. It contains:
- diagrams used in the analysis and design stage
- descriptions of procedures and subroutines used
- data structures
- algorithm designs
- annotated code listings
- variable lists
What is a backup and why are they important?
Back ups are additional copies of all data files that an organisation wishes to protect. It allows the system to be restores in case the original gets lost somehow. Frequent backups lead to easy recovery, but can take up a lot of storage.
What is a generation file backup system?
The three most recent versions of the files are stored, grandfather-father-son. If one is corrupted, the other versions are still available. Data should be stored off site in case of disaster.
What is an incremental backup?
Only backs up data that has changed and writes over older backups. It saves storage space and time, but only one backup is available.
What is a delta change backup?
Only data changed since the previous backup is backup up. The original back up is also maintained in case data needs to be restored. This is quicker than a full back up.
