The systems analysis and design

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7.1 The systems life cycle: Analysis

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Correcting data for analysis the current system

The systems analyst must balance the mix of these method, depending on the number of people who may be able to supply fist-hand information, the amount time available and the detail required from these people.

Four main ways to correct information:

  • Interview +know actual problem -spending a lot of time.
  • Observation +can see the real problem -people feel uncomfortable.
  • Questionnaires +able to ask many people -limited rage of answers
  • Using existing documentation +help people to understand – not clear

Recording and analyzing information about the current system

Relevant questions will include:

  • Where does data originate? What does it consist of?
  • How does data enter the system? Who enters the data?
  • What data processing takes place? What algorithms are used?
  • How is data stored? How secure is it?
  • How data is used? Who uses ot?

7.2 The systems life cycle: Design and development

The design stage

The design stage is about identifying modules that will make up the solution to the problem. The most element of this stage is that of file structure. At the end of the design stage the system analyst will have design on the:

  • data structure
  • file formats
  • input and output formats
  • module specifications
  • relationships that need to exist between the different modules (and systems) in the organisation.

Design tasks

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System flowcharts

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The develop stage

They will need to decisions about:

  • the fields (include the key fields) that are necessary in each data table
  • the data to be stored in each field
  • the length of each field
  • the links between each data table.

Design tasks

Designing –  data capture forms, screen layout, output report, other printed outputs, filed structures and tables and a testing strategy.

Producing – data flow diagrams and system flowcharts or pseudo code to describe the system and diagram to describe the relationship between each module in the systems.

Selecting and defining – hardware requirements, software requirement, validation rules and verification models.

Validation

Validation is an automatic computer check to ensure that the data entered is sensible and reasonable. It does not check the accuracy of data. For example, a secondary school student is likely to be aged between 11 and 16. The computer can be programmed only to accept numbers between 11 and 16.

Data validation is very important. The designers will have to be ensure that they have designed appropriate validation routines that will test the data input to the system.

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7.3 The systems life cycle: Testing and implementation

The users interface

Input devices:

  • The scanner at the checkout
  • hand-held scanners for counting and recording stock – these might also be used to record special offers or price reductions
  • the EPOS/EFTPOS terminal
  • a Chip and PIN reader.

Output devices:

  • a display screen for the checkout operator
  • a display screen for the customer
  • a printer for itemized receipts
  •  a portable bar-code printer attached to the hand-held scanner

The analyst must also check that:

  • any messages and user in structions are clear
  • all displays are easy t read
  • the display is accessible to all customers – it may needed to be adjustable.

Testing data entry

The purpose of test data is to make sure that:

  • inputs to the system are valid
  • outputs from the system are accurate
  • outputs are presented clearly.

The data that is used to test a system will fall into four categories

  1. Normal test data.
  2. Live data.
  3. Extreme test data.
  4. Abnormal test data.

Implementation

Implementation means that the old system is replaced by the new system. Implementation can happen in anyone of four ways:

  1. Direct changeover. The old system shuts down and the new system is implemented immediately, without running two sys
  2. Parallel running.
  3. Phased implementation.

The choice of which type of implementation to use will depend on certain factors.

Test # Field name Data type Test data Test type What testing Test okay?
1 FirstName Short Text Freddie Normal Data is accepted Yes
2 Short Text Austin Normal Data is accepted Yes
3 Short Text Lookkaew27 Abnormal Data rejected No
4 Short Text Tan Normal Data is accepted Yes
5 FamilyName Short Text Brooks Normal Data is accepted Yes
6 Short Text Sang_tong Abnormal Data rejected No
7 Short Text Ninth9 Abnormal Data rejected No
8 Short Text Kwala* Abnormal Data rejected No
9 TG Short Text One Normal Data is accepted Yes
10 Short Text Two Normal Data is accepted Yes
11 Short Text Three Normal Data is accepted Yes
12 Short Text Four Normal Data is accepted Yes
13 DoB Date/Time 14/02/2020 Abnormal Data rejected No
14 Date/Time 14/05/2013 Normal Data is accepted Yes
15 Date/Time 31/12/1974 Normal Data is accepted Yes
16 Date/Time 32/33/34 Abnormal Data rejected No
17 Gender Short Text Man Abnormal Data rejected No
18 Short Text Woman Abnormal Data rejected No
19 Short Text Female Normal Data is accepted Yes
20 Short Text Male Normal Data is accepted Yes
21 Instrument Short Text Blueguitar? Abnormal Data rejected No
22 Short Text Flute Normal Data is accepted Yes
23 Short Text Violin Normal Data is accepted Yes
24 Short Text Piano Normal Data is accepted Yes
25 Own Yes/No N Normal Data is accepted Yes
26 Yes/No Maybe Abnormal Data rejected No
27 Yes/No Yes Normal Data is accepted Yes
28 Yes/No Y Normal Data is accepted Yes
29 SerialNo Short Text K32TUVE Normal Data is accepted Yes
30 Short Text GEW2^*GHK Abnormal Data rejected No
31 Short Text AFH43GS29G Abnormal Data rejected No
32 Short Text L3F4RHJX Normal Data is accepted Yes
33 Orchestra Yes/No Sometimes Abnormal Data rejected No
34 Yes/No No Normal Data is accepted Yes
35 Yes/No Not really Abnormal Data rejected No
36 Yes/No Yes Normal Data is accepted Yes
37 Teacher Short Text Miss N Boyd Normal Data is accepted Yes
38 Short Text Miss 87 days Abnormal Data rejected No
39 Short Text Mrs M Potts Normal Data is accepted Yes
40 Short Text Mrs something whose begin with N Abnormal Data rejected No
41 LessonWeek Number 1 Normal Data is accepted Yes
42 Number 0.5 Abnormal Data rejected No
43 Number 5.0 Abnormal Data rejected No
44 Number 2.03 Abnormal Data rejected No
45 Costweek Currency 5 Abnormal Data rejected No
46 Currency 5.00 Normal Data is accepted Yes
47 Currency 9 Abnormal Data rejected No
48 Currency 0.6 Abnormal Data rejected No
49 Notes Short Text +5 Abnormal Data rejected No
50 Short Text ^^* Abnormal Data rejected No
51 Short Text XD Abnormal Data rejected No
52 Short Text – Abnormal Data rejected No

7.4 The systems life cycle: Documentation and evaluation

Technical documentation

  • Validation rules
  • Hardware and software requirements
  • Input and output formats
  • Programming langue

User documentation

  • How to save a file
  • How to search, sort and print
  • FAQ
  • How to load software/install/run software

Systems flow charts

Evaluation

Evaluation actually takes place during each stage of the cycle, as the analyst and team work out what is required, how to solve problems and implement and test solutions. There is also a distinct evaluation stage that comes at the end of the entire development cycle. As with all other stages of the systems life cycle there will be a report. There are two considerations:

  1.  Why do we need to evaluate the new system?

Organisations need to establish how well the new system works in order to be able to report to the systems analysts.

2.   How do we make an evaluation?

  • Make a comparison between the new system and the one it has replaced.
  • Once the systems has been in operation for a short time period it will be possible to identify the limitations  of, and quite possibly improvement to, the system.
  • Equally important are the views of the users who are using the system on a day-to-day basis.