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Chapter 4 - System Design - Coggle Diagram
Chapter 4 - System Design
User Interface Design(UI) - Describes how users interact with a computer system.
4.1 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.
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
Today, designers strive to translate user behavior, needs, and desires into an interface that users don’t really notice.
Main objective is to create a user-friendly design that is easy to learn and use
Principles of user-centered design:
i. Understand the Business - The interface designer must understand the underlying business functions and how the system supports individual, departmental, and enterprise goals.
ii. Maximize Graphical Effectiveness - A well-designed interface can help users learn a new system rapidly, and be more productive.
iii. Think Like a User - A systems analyst should understand user experience, knowledge, and skill levels.
iv. Use Models and Prototypes -From a user’s viewpoint, the interface is the most critical part of the system design because it is where he or she interacts with the system
v. Focus on Usability - The user interface should include all tasks, commands, and communications between users and the information system.
vi. Invite Feedback - Even after the system is operational, it is important to monitor system usage and solicit user suggestions.
vii. Document Everything - You should document all screen designs for later use by programmers.
Use Interface Guidelines: It is important to design a user interface that is easy to use, attractive, and efficient.
8 Basic Guidelines
1) Design a transparent interface
2) Create an interface that is easy to learn and use
3) Enhance user productivity
4) Make it easy for users to obtain help or correct errors
5) Minimize input data problems
6) Provide feedback to users
7) Create an attractive layout and design
8) Use familiar terms and images
Screen Elements & Controls
Menu Bar
Toolbar
Command button
Dialog box
Text box
Toggle button
List box- scroll bar
Drop-down list box
Option button, radio button
Check box
Calendar control
Switchboard
Types of Reports
a) Detail reports - produces one or more lines of output for each record processed
b) Exception reports - displays only those records that meet a specific condition or conditions
c) Summary reports - Upper-level managers often want to see total figures and do not need supporting details
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.
The report footer, which appears at the end of the report, can include grand totals for numeric fields and other end-of-report information.
Column heading alignment
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.
Many designers prefer Example 4, where headings are left-justified over alphanumeric fields and right-justified over numeric fields.
Design report principles:
Column spacing - 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.
Grouping detail lines - It is meaningful to arrange detail lines in groups, based on a control field.
Repeating fields - User involvement is essential, but users often don’t know what they want without seeing samples.
Consistent design - Look and feel are important to users, so reports should be uniform and consistent.
Source Documents
Collects input data
Trigger or authorizes an input action and provides a record of the original transaction
Paper based, but also an provided online
Good form layout makes the form easy to complete and provides enough space, both vertically and horizontally, for users to enter the data.
The heading zone usually contains the company name or logo and the title and number of the form.
The main part of the form, called the body zone, usually takes up at least half of the space on the form and contains captions and areas for entering variable data.
- Finally, the authorization zone contains any required signatures.
Information should flow on a form from left to right and top to bottom to match the way users read documents naturally.
The same user-friendly design principles also apply to printed forms such as invoices and monthly statements, except that heading information usually is preprinted.
4.2 Input & Output Design
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 data is entered ]
To ensure the quality , accuracy and timelines of input data
Good input design requires attention to human factors as well as technology issues
Data Entry Screens
Guidelines
1) Restrict user access to screen locations where data is entered
2) Provide a descriptive caption for every field, and show the user where to enter the data and the required or maximum field size
3) Display a sample format if a user must enter values in a field in a specific format - separator
4) Require an ending keystroke for every field
5) Do not require users to type leading zeroes for numeric fields
6) Do not require users to type trailing zeroes for numbers that include decimals
7) Display default values so operators can press the ENTER key to accept the suggested value
8) Use a default value when a field value will be constant for successive records or throughout the data entry session
9) Display a list of acceptable values for fields, and provide meaningful error messages
10) Provide a way to leave the data entry screen at any time without entering the current record
11) Provide users with an opportunity to confirm the accuracy of input data before entering it
12) Provide a means for users to move among fields on the form
13) Design the screen form layout to match the layout of the source document
14) Allow users to add, change, delete, and view records
15) Provide a method to allow users to search for specific information
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.
Batch Input
Data entry is performed on a specified time schedule [ daily, weekly, monthly, or longer ]
Example : a school enters all grades for the academic term in a batch
Online Input
Batch input - used in specific situations but most business activity requires online data entry
Examples : Automatic teller machines (ATMs) that read data strips on bank cards
8 types of data validation rules: 1) Sequence check 2) Existence check
3) Data type check
4) Range check
5) Reasonableness check
6) Validity check
7) Combination check
8) Batch controls
