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CHAPTER 4 : SYSTEM DESIGN - Coggle Diagram
CHAPTER 4 : SYSTEM DESIGN
TOPIC 4.1
4.1.1 User Interface Design
Evolution of the User Interface
Often, the user interface mainly consisted of process-control screens that allowed the user to send commands to the system
That approach worked well with traditional systems that simply transformed input data into structured output.
User-centered system
Requires an understanding of human-computer interaction and user-centered design principles
Human-Computer Interaction
Human-computer interaction (HCI) describes the relationship between computers and people who use them to perform their jobs
The human-computer interface started in the 1980s with users typing complex commands in green text on a black screen.
Then came the graphical user interface (GUI), which was a huge improvement, because it used icons, graphical objects, and pointing devices.
Today, designers strive to translate user behavior, needs, and desires into an interface that users don’t really notice.
Industry leaders Microsoft and IBM both devote considerable resources to user interface research.
Principles of user-centered design
Understand the Business
The interface designer must understand the underlying business functions and how the system supports individual, departmental, and enterprise goals
Maximize Graphical Effectiveness
Also, in a graphical environment, a user can display and work with multiple windows on a single screen and transfer data between programs.
. Think Like a User
The interface should use terms and metaphors that are familiar to users.
Use Models and Prototypes
You can present initial screen designs to users in the form of a storyboard, which is a sketch that shows the general screen layout and design
Focus on Usability
The user interface should include all tasks, commands, and communications between users and the information system.
Invite Feedback
You can determine if system features are being used as intended by observing and surveying users
. Document Everything
If you are using a CASE tool or screen generator, number the screen designs and save them in a hierarchy similar to a menu tree.
4.1.2 User Interface Design Guidelines
Design a transparent interface
Facilitate the system design objectives, rather than calling attention to the interface
Create an interface that is easy to learn and use
Select only those images that users can understand easily, and provide on-screen instructions that are logical, concise, and clear
Enhance user productivity
Organize tasks, commands, and functions in groups that resemble actual business operations
Make it easy for users to obtain help or correct errors
Provide user-selected Help and context-sensitive Help
Minimize input data problems
Establish a list of predefined values that users can click to select
Provide feedback to users
Display messages at a logical place on the screen, and be consistent
Create an attractive layout and design
Use appropriate colors to highlight different areas of the screen
Use familiar terms and images
Provide a Windows look and feel in your interface design if users are familiar with Windows-based applications
4.1.3 User Interface Components
Screen Elements & Controls
List box – scroll bar
Drop-down list box
Option button, or radio button
Check box
Calendar control
Switchboard
Screen Elements & Controls
Menu bar
Toolbar
Command button
Dialog box
Text box
Toggle button
4.1.4 Source Documents
Good form layout makes the form easy to complete and provides enough space, both vertically and horizontally, for users to enter the data.
A form should indicate data entry positions clearly using blank lines or boxes and descriptive captions.
The same user-friendly design principles also apply to printed forms such as invoices and monthly statements, except that heading information usually is preprinted.
TOPIC 4.2
INPUT & OUTPUT DESIGN
4.2.1 Input Design & Technology Issues
quality of the output = quality of the input
garbage in, garbage out (GIGO)
the best time to avoid problems is when the data is enterde
4.2.2 Objectives of Input Design
to ensure the quality, accuracy, and timeliness of input data
Good input design requires attention to human factors as well as technology issues
4.2.3 Guidelines For Data Entry Screen Design
Data Entry Screens
Guideline
Restrict user access to screen locations where data is entered
Provide a descriptive caption for every field, and show the user where to enter the data and the required or maximum field size
Display a sample format if a user must enter values in a field in a specific format - separator
Require an ending keystroke for every field
Do not require users to type leading zeroes for numeric fields
Do not require users to type trailing zeroes for numbers that include decimals
Display default values so operators can press the ENTER key to accept the suggested value
Use a default value when a field value will be constant for successive records or throughout the data entry session
Display a list of acceptable values for fields, and provide meaningful error messages
Provide a way to leave the data entry screen at any time without entering the current record
Provide users with an opportunity to confirm the accuracy of input data before entering it
Provide a means for users to move among fields on the form
Design the screen form layout to match the layout of the source document
Allow users to add, change, delete, and view records
Provide a method to allow users to search for specific information
4.2.4 Data Capture vs Data Entry
Data capture
- service in which data is captured via tick or check boxes and other items where areas are filled in with simple lines or shapes in order to get the right answer
Data entry
- manually entered text, copying exactly what the person who filled out the feedback form has written.
4.2.5 Input & Data Entry Method
a. Batch Input
data entry is performed on a specified time schedule [ daily, weekly, monthly, or longer ]
example: batch input occurs when a payroll department collects time cards at the end of the week and enters the data as a batch
b. Online Input
batch input - used in specific situations
Advantages:
immediate validation
availability of data
4.2.6 Input Mask & Validation Rules
8 types of data validation rules
Sequence check
used when the data must be in some predetermined sequence
Existence check
used for mandatory data items
Data type check
tests to ensure that a data item fits the required data type
Range check
tests data items to verify that they fall between a specified minimum and maximum value
Reasonableness check
identifies values that are questionable, but not necessarily wrong
Validity check
used for data items that must have certain values
Combination check
referential integrity - value entered must refer to another value
Batch controls
performed on 2 or more fields to ensure that they are consistent or reasonable when considered together
4.3.8 Output Technology
Although business information systems still provide most output as screen displays and printed matter, technology is having an enormous impact on how people communicate and obtain information.
Besides printed report, system also should consider various types of output technologies
Internet based information delivery
To support the explosive growth in e-commerce, Web designers must provide user-friendly screen interfaces that display output and accept input from customers.
Specialized form of output
An incredibly diverse marketplace requires many forms of specialized output and devices such as these:
4.2.9 Types Of Reports
a. Detail reports
figure shows a simple detail report of employee hours for a chain of retail stores
example : an employee paycheck that has multiple output lines for a single record
b. Exception reports
displays only those records that meet a specific condition or conditions
example : a credit manager might use an exception report to identify only those customers with past due accounts
c. Summary reports
Upper-level managers often want to see total figures and do not need supporting details
example : a sales manager might want to know total sales for each sales representative, but not want a detail report listing every sale made by them
4.2.10 Design Report Principles
Report headers and footers
The report header, which appears at the beginning of the report, identifies the report, and contains the report title, date, and other necessary information
Every page should include a page header, which appears at the top of the page and includes the column headings that identify the data.
Either a page header or a page footer, which appears at the bottom of the page, is used to display the report title and the page number
Column heading alignment
In Example 1, the left-justified column headings do not work well with numeric fields because the amount 1.25 would print past the right edge of the AMOUNT heading.
Column spacing
A crowded report is hard to read, and large gaps between columns make it difficult for the eye to follow a line.
Columns should stretch across the report, with uniform spacing and suitable margins at top, bottom, right, and left
Some report designers use landscape orientation when working with a large number of columns; others prefer to break the information into more than one report.
Field order
Fields should be displayed and grouped in a logical order.
For example, the report shown in Figure shows the detail lines printed in alphabetical order within store number, so the store number is in the left column, followed by the employee name
Grouping detail lines
Often, it is meaningful to arrange detail lines in groups, based on a control field
For example, using the department number as a control field, individual employees can be grouped by department.
Repeating fields
User involvement is essential, but users often don’t know what they want without seeing samples.
For example, consider the issue of repeating fields. The sample report in Figure repeats the store number on every row. Is that a good thing? The best advice is to ask users what they think, and be guided accordingly.
Consistent design
A system produces multiple reports, each report should share common design elements.
For example, the date and page numbers should print in the same place on each report page
4.2.12 Input & Output Controls & Security
Output control & security
Output security protects privacy rights and shields the organization’s proprietary data from theft or unauthorized access
All sensitive reports should be stored in secure areas.
Input control & security
That means that you must provide an audit trail that records the source of each data item and when it entered the system
In addition to recording the original source, an audit trail must show how and when data is accessed or changed, and by whom.
Data security policies and procedures protect data from loss or damage, which is a vital goal in every organization.
If the safeguards are not 100% effective, data recovery utilities should be able to restore lost or damaged data
