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AICT > Chapter 4 SYSTEMS DEVELOPMENT LIFE CYCLE > Flashcards

Chapter 4 SYSTEMS DEVELOPMENT LIFE CYCLE Flashcards

1
Q

What is system analysis?

A

It is the term which deals with the in depth study or analysis of systems and their daily functioning.

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2
Q

Who is a system analyst?

A

A systems analyst is a person who makes use of computers and related systems to design new IT solutions, modify, enhance or adapt existing systems and integrate new features or improvements, to improve business efficiency and productivity all together.

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3
Q

what are the Functions of a system analyst?

A

1 examine existing IT systems and business models;
2 analyses systems requirements;
3 undertake product development;
4 Implement, configure and test feasible solutions

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4
Q

Why carry out Systems analysis?

A

1 A System is computerized and may be out of date – > it needs replacing
2 Small company has a computer system but its use if very limited + could be improved to allow many more aspects of the business to become computerized.

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5
Q

What is feasibility study?

A

It is the measure and the study of how beneficial the development of the system would be to the organization in terms of cost.

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6
Q

What are The Stages of Systems Life cycle?

A

The systems life cycle is so named because it is a circular process. There is no real start and finish point, because after a new system has been evaluated this leads to further improvements being needed and so the whole process starts over again.

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7
Q

What are the different stages?

A 
1 planning
2 Analysis
3 Design
4 Coding 
5 testing 
6 Maintenance
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8
Q

The purpose of analyzing the existing system is?

A

1 To see how data flows around the system.
2 To see what data comes in to the company,
3 How it is processed and
4 What outputs they produce?
5 Only after this has been determined will the analyst decide on what sort of computer system should be implemented.

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9
Q

What does the Analysis involve?

A
  • Fact finding – this is usually done in four ways.
  • Understanding the current system
  • Produce data flow diagrams
  • Identify the user requirements
  • Interpret the user requirements
  • Agree the objectives with the user
  • Collect data from the current system
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10
Q

What are the different methods used to gather information?

A

1 Questionnaires
2 Interviews
3 Observations
4 Analyzing documents

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11
Q

What are Questionnaires?

A

They are normally preset for a large group of persons.
Mainly consists of 2 types:
1 Closed questions (multiple choice)
2 Open questions.

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12
Q

Advantages of using questionnaires

A

1 Can get answers from a lot of people in a relatively short space of time
2 They provide lots of data for analysis and the more data sets, the more accurate the analysis
3 Everyone answers the same questions i.e. same information is requested. Reduces bias.
4 Allows people to answer at a time convenient to them
5 If anonymous, perhaps more honest answers will be provided
6 Questions can be planned ahead of time by the analyst

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13
Q

Disadvantages of using questionnaires

A

1 Only as good as the questions being asked. If the questions are poorly worded or they are biased then the data obtained might not give an accurate picture.
2 Can be difficult for the analyst to ask the right questions if they are unfamiliar with the system
3 They are impersonal, people may be more open face to face discussions
4 The response rate may be poor - especially if people are busy or don’t see the benefit in answering
5 Difficult to allow people to expand on their answers, especially with closed questions

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14
Q

What are interviews?

A

They are normally used for obtaining information from a group of selected individuals.

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15
Q

Advantages of conducting interviews

A

1 Excellent for personal contact and understanding with the user
2 Can elicit hard-to-quantify information and knowledge
3 Extra detail can be drawn out on the spot
4 Opinions can be aired and considered by people in the group

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16
Q

Disadvantages of conducting interviews

A

1 Take up a lot of time for both individuals and the analyst
2 Must be well structured to be efficient - it is easy to waste time in an interview
3 Only practical for a limited number of people
4 Less quantitative than a questionnaire
5 People have to be available

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17
Q

What is observation?

A

Observation is a process where the observer analyses the daily undertakings of organizations or people to see how tasks are completed and delivered.
Mainly two types:
Direct observation
Indirect observation

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18
Q

Advantages of observations

A

1 Useful if there are no documents involved the system
2 Can spot inefficiencies in the system
3 Can help identify persistent problems
4 Analyst can rapidly understand first-hand what the system needs to do
5 Users can impart their experience of the system directly

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19
Q

Disadvantages of observations

A

1 People don’t like being watched
2 Take up a lot of time
3 Analyst may be in the way on a busy day
4 Not so efficient at capturing quantitative data for analysis

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20
Q

What is Examining documents?

A

In this process the analyst brings in all the relevant documents where they will be examined to determine the way they are input, manipulated, sorted and output.

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21
Q

Advantages of analyzing documents

A

1 Excellent for tracking data flow
2 Excellent for identifying data types and formats
3 Useful to identify inefficient data flows so making the new system better

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22
Q

Disadvantages of analyzing documents

A

1 There may be other important data that are not actually in the documents
2 Cannot capture the efficiency of the process. Speed/delays etc
3 Does not help with understanding how people actually use the data

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23
Q

What is the design stage?

A

Once the analysis has taken place and the systems analyst has some idea of the scale of the problem and what needs to be done, the next stage is to design the key parts of the recommended system

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24
Q

What are the list of tasks that are usually done in the design phase?

A
  • Design the data capture forms/input forms
  • Design the screen layouts
  • Design output forms and reports
  • Produce systems flowcharts and/or pseudocode
  • Select/design any validation rules that need to be used
  • Select the most appropriate data verification method(s)
  • File structures/tables need to be designed/agreed
  • Select/design the hardware requirements for the new system
  • Select/design the software requirements
  • Produce any algorithms or program flowcharts
  • Design a testing strategy/plan
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25
Q

What is Off-the-shelf software?

A

Off-the-shelf software, which is created for use by a large range of customers - it tends to be quite general-purpose.

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26
Q

What is Purpose-built software?

A

Purpose-built software (Custom-written software), which is designed and written specifically for one customer.

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27
Q

Advantages of Off-the-shelf software

A
  1. is cheap
    2 Available straight away
    3 Has help lines to deal to with a wide range of problems
28
Q

Disadvantages of Off-the-shelf software

A

1 can be difficult to adapt to the particular use
2 May have several distracting extra features
3 May not match up with existing system and software use

29
Q

Advantages of purpose-built

A

1 designed specifically for the task
2 does not have to be adapted for the use
3 Programmers can make any changers required

30
Q

Disadvantages of Purpose-built

A

1 is more expensive
2 Support is limited to the team of programmers
3 Can take long to develop?

31
Q

What is Implementation?

A

Once the “final” system has been designed it is then necessary to put together the hardware and software and introduce the new system. There are many stages in this complicated process:

Produce the documentation; there are two basic types here to consider:
1 Technical documentation
2 User Documentation

32
Q

What is a technical documentation?

A

Technical documentation refers to the documentation that describes how a product or service operates.

33
Q

What is user documentation?

A

User documentation refers to the documentation for a product or service provided to the end users. The user documentation is designed to assist end users to use the product or service.

34
Q

Contents of technical documentation

A
  • Program listing/coding
  • Programming language(s) used
  • Flowchart/algorithm
  • Purpose of the system/program/software
  • Input formats
  • Hardware requirements
  • Software requirements
  • Minimum memory requirements
  • Known “bugs” in the system
  • List of variables used (and their meaning/description)
  • File structures
  • Sample runs (with results and actual test data used)
  • Output formats
  • Validation rules
35
Q

Contents of user documentation

A
  • How to load/run the software
  • How to save files
  • How to do a search
  • How to sort data
  • How to do print outs
  • How to add, delete or amend records
  • The purpose of the system/program/software package
  • Screen layouts (input)
  • Print layouts (output)
  • Hardware requirements
  • Software requirements
  • Sample runs (with results and actual test data used)
  • Error handling/meaning of errors
  • Troubleshooting guide/help lines/FAQs
  • How to log in/log out
36
Q

What are validation and its types?

A

Validation is the process of determining the accuracy of data. The process is used to ensure that data conforms to given specifications.

37
Q

What are the types of validation checks?

A 
1 Range check
2 Length check 
3 Format/Picture check
4 Invalid character check
5 Check digit
38
Q

What is range check?

A

Range check: Used on data containing numeric data (e.g. workers can work for a minimum of 0
hours and a maximum of 9 hours)

39
Q

What is Length check?

A

Length check: this can be used for text fields

40
Q

What is Format/Picture check?

A

Format/Picture check: check if a specific field has a specific format. For instance it must contain 4 numbers followed by a letter.

41
Q

What is Invalid character check?

A

Invalid character check: input is checked in order to ensure that it is digits or all text

42
Q

What is Check digit?

A

Check digit: this is when a calculation is performed on a long string of digits which produces an extra digit which is added to the end of the string of digit.

43
Q

What is the testing stage?

A

It is important that the systems analyst produces a test plan. The test plan will consist of a list of test data together with the results expected to be produced by the system (expected results). The systems analyst will then make a note of the results which the system in fact produced when this data was used (actual results). There will also be a note made by the analyst of any comments if there are differences between the actual results and the expected results.

44
Q

What are the Types of data used for testing?

A
  1. Normal data
  2. Extreme data
  3. Abnormal data
45
Q

what is normal data?

A

Normal data is data that is acceptable. It should not produce an error when input into the system.
Example:
In a pay slip no-one should have worked more than 65 hours or less than 0 hours. So data that
lies within that is entered and if an error message is produced it means that there is a problem with the system.

46
Q

What is extreme data?

A

Extreme data is used only when a range of data is input.
Things like name and address will not have any extreme data.
But in the case of a pay slip where the most amount of hours worked could be 65 and the lowest could be 0; entering 65 or 0 would be considered as extreme data.

47
Q

What is Abnormal Data?

A

Abnormal data is data this not acceptable.
For example:
You wouldn’t want alphabetic characters in a numeric field.
• When data range is used; any number outside that range will be considered as abnormal.
• For instance with the pay slip; any number that lies outside the range of 0 and 65 hours will be considered as abnormal data.

48
Q

What are the different methods of implementation?

A
  1. Parallel running:
  2. Direct change over
  3. Phased implementation
  4. Pilot running
49
Q

What is Parallel running?

A

This is when the new system is run alongside the old system, meaning that the results on the new system can easily be checked against those of the old system.

50
Q

Advantages of Parallel running?

A

1 If anything goes wrong with the new system, the old system will act as a back-up.
2 The outputs from the old and new systems can be compared to check that the new system is running correctly

51
Q

Disadvantages of Parallel running?

A

1 Higher running costs as there are two systems running

2 It takes longer than the other methods

52
Q

What is Direct change over?

A

The existing system is replaced by the new one instantly. This method should only be used if the new system has been tested thoroughly. There is a major risk taken here because if the old system is shut down it cannot be reintroduced.

53
Q

Advantages of direct change over?

A

1 It cost less than parallel running as only one set of workers are required
2 it is a quick method

54
Q

Disadvantages of direct change over?

A

1 if a problem arises there is no back up system

2 it may be difficult to make improvements to the new system and keep it working

55
Q

What is phase implementation?

A

This is when the new system is introduced to the system one part at a time. This way any problems that arise can be overcome and as soon as the system is working fine another aspect can be introduced. This carries on until all aspects have been introduced into the system.

56
Q

Advantages of phase implementation

A

1 if the introduced part of the system fails all the other parts are still working
2 workers have time to get used to the new system

57
Q

Disadvantages of phase implementation

A

1 Slow method of implementation compared to direct changeover
2 if the new system doesn’t work properly there is no way of going back to the old system

58
Q

What is Pilot running?

A

This method is usually taken up by large organizations. The new system is implemented in one of the branches of the organization while other branches continue with the existing system.

59
Q

Advantages of Pilot running

A

1 if the system doesn’t work not all the branches are affected
2 Later branches benefit by learning from the mistakes made by earlier branches

60
Q

Disdvantages of Pilot running

A

1 Slow method of implementation

61
Q

What is System Maintenance and Evaluation?

A

Once a system is up and running it is necessary to do some evaluation and carry out maintenance if necessary.

62
Q

What are the task to be done in system evaluation?

A

1 Compare final solution with the original requirement
2 Identify any limitations in the system
3 Identify any necessary improvements that need to be made
4 Evaluate the user’s responses to using the new system
5 Compare test results from new system with results from the old system
6 Compare performance of new system with performance of old system

63
Q

What are the Tasks to be done in system maintenance

A

1 Update hardware as new items come on the market or the company changes in any way which requires new devices to be added/updated
2 Update software if necessary if company structure changes or legislation is introduced which affects how the company operates

64
Q

What are the uses of a Gantt Chart?

A

1 Gantt charts which show all stages/tasks to be done
2 Gantt charts which show the critical path(s)
3 Gantt charts which show key project milestones
4 Gantt charts also show:
- Number of days to do a task
- Progress of tasks as % complete
- Progress versus expected time to do work
- How tasks are all linked together

65
Q

Use of PERT Charts

A

Use of software (such as Microsoft Project) which allows progress to be tracked

66
Q

what are System flowcharts ?

A

System flowcharts are used to show how all the components in a system link together (e.g. input, storage, output, processing, etc.). They are very different to normal flowcharts since they don’t go into detail of how something is actually done – they are a general overview.

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