Design of input

SYSTEMS ANALYSIS AND DESIGN METHODS 6th Edition Whitten Bentley Dittman
C H A P T E R
16
INPUT DESIGN
AND
PROTOTYPING
Irwin/McGraw-Hill Copyright © 2004 The McGraw-Hill Companies. All Rights reserved

Whitten SYSTEMS ANALYSIS AND DESIGN METHODS 6th Edition Bentley Dittman
Chapter Sixteen Input Design & Prototyping
• Define the appropriate format and media for a
computer input.
• Explain the difference between data capture, data
entry, and data input.
• Identify and describe several automatic data collection
technologies.
• Apply human factors to the design of computer inputs.
• Design internal controls for computer inputs.
• Select proper screen-based controls for input attributes
that are to appear on a GUI input screen.
• Design a web-based input interface.

Chapter Map

Data Capture and Data Entry
Data capture – the identification and acquisition of
new data (at its source).
– Source documents – forms used to record
business transactions in terms of data that
describe those transactions.
Data entry – the process of translating the source
data or document (above) into a computer readable
format.

Data Processing
Data processing is all processing that occurs on
the data after it is input from a machine readable
form.
– In batch processing, the entered data is collected
into files called batches and processed as a
complete batch.
– In on-line processing, the captured data is
processed immediately
– In remote batch processing, data is entered and
edited on-line, but collected into batches for
subsequent processing.

Input Implementation Methods
• Keyboard
• Mouse
• Touch Screen
• Point-of-sale terminals
• Sound and speech
• Automatic data capture
– Optical mark recognition (OMR)
• Bar codes
– Optical character recognition (OCR)
– Magnetic Ink
– Electromagnetic transmission
– Smart cards
– Biometric

Taxonomy for Computer Inputs
Process Method Data Capture Data Entry Data Processing
Keyboard Data is usually captured on
a business form that
becomes the source
document for input. Data
can be collected real-time.
Data is entered via keyboard.
This is the most common input
method but also the most
prone to errors.
OLD: Data can be collected
into batch files (disk) for
processing as a batch.
NEW: Data is processed as
soon as it has been keyed.
Mouse Same as above. Used in conjunction with
keyboard to simplify data
entry. Mouse serves as a
pointing device for a screen.
Same as above, but the use
of a mouse is most commonly
associated with online and
real-time processing.
Touch Screen Same as above. Data is entered o a touch
screen display or handheld
device. Data entry users either
touch commands and data
choices or enter data using
handwriting recognition.
On PCs, touch screen choices
are processed same as
above. On handheld
computers, data is sorted on
the handheld for later
processing as a remote batch.
Point of Sale Data is captured as close
to the point of sale as
humanly possible. No
source documents.
Data is often entered directly
by the customer or by an
employee directly interacting
with the customer.
Data is almost always
processed immediately as a
transaction or inquiry.

Taxonomy for Computer Inputs (continued)
Sound Data is captured as close to
the source as possible,
even when the customer is
remotely located.
Data is entered using touch-tones
(typically from a
telephone). Usually requires fairly
rigid command menu structure
and limited input options.
processed immediately as
a transaction or inquiry.
Speech Same as sound. Data (and commands) is spoken.
This technology is not as mature
and is much less reliable and
common than other techniques.
processed immediately as
a transaction or inquiry.
Optical Mark Data is recorded on optical
scan sheets as marks or
precisely formed letter,
numbers, and punctuation.
Eliminates the need for data
entry.
processed as a batch.
Magnetic Ink Data is usually prerecorded
on forms that are
subsequently completed by
the customer. The customer
records additional
information on the form.
A magnetic ink reader reads the
magnetized data. The customer-added
data must be entered
using another input method.
processed as a batch.

Taxonomy for Computer Inputs (concluded)
Electromagnetic Data is recorded directly on
the object to be described
by data.
Data is transmitted by radio
frequency.
processed immediately.
Smart Card Data is recorded directly on
a device to be carried by the
customer, employee, or
other individual that is
described by that data.
Data is read by smart card
readers.
processed immediately.
Biometric Unique human
characteristics become data
Data is read by biometric
sensors. Primary applications are
security and medical monitoring
Data is processed
immediately.

Automatic Identification: Bar Codes

Input Design Guidelines
• Capture only variable data.
– Not data that can be looked up.
• Do not capture data that can calculated or stored in
computer programs as constants.
– Extended Price, Federal Withholding, etc.
• Use codes for appropriate attributes.

Source Document / Form Design Guidelines
• Include instructions for completing the form.
• Minimize the amount of handwriting.
• Data to be entered (keyed) should be sequenced top-to-
bottom and left-to-right.
• When possible use designs based on known
metaphors.

Good Flow in a Form

Bad Flow in a Form

Metaphoric Screen Design
• Other useful metaphors include a check, a register, and a calendar.
• Pictures of objects can also be metaphors. For example, many Web
sites use a picture of each credit card accepted instead of the names.

Internal Controls for Inputs
• The number of inputs should be (to minimize risk of
lost transactions).
– For batch processing
• Use batch control slips (batch no., no. of documents, control
totals)
• Use one-for-one checks against post-processing detail reports
– For on-line systems
• Log each transaction as it occurs to a separate audit file
• Validate all data
– Existence checks
– Data-type checks
– Domain checks
– Combination checks
– Self-checking digits
– Format checks

Repository-Based Prototyping and Development
Define
properties and
constraints for a
reusable field

Repository-Based Prototyping and Development
Define data
validation code
for a field

Common GUI Controls (Windows and Web)
1. Text boxes
2. Radio
buttons
3. Check boxes
4. List boxes
5. Drop down
lists
6. Combination
boxes
7. Spin boxes
8. Buttons

Common GUI Controls Uses
• Text boxes
– When the input data values are unlimited in scope
• Radio buttons
– When data has limited predefined set of mutually exclusive values
• Check boxes
– When value set consists of a simple yes or no value
• List boxes
– When data has a large number of possible values
• Drop down lists
– When data has large number of possible values and screen space
is too limited for a list box
• Combination boxes
– When need to provide the user with option of selecting a value from
a list or typing a value that may or may not appear in the list
• Spin boxes
– When need to navigate through a small set of choices or directly
typing a data value

Advanced Controls (mostly Windows interfaces)
1. Drop down
calendars
2. Slider edit
controls
3. Masked edit
controls
4. Ellipsis
controls
5. Alternate
numerical
spinners
6. Check list
boxes
7. Check tree
boxes

Advanced Controls (mostly Windows interfaces)

Automated Tools for Input Design and Prototyping
• Old Tools
– Record Layout Charts
– Display Layout Charts
• Newer Prototyping Tools
– Microsoft Access
– CASE Tools
– Visual Basic
– Excel
– Visio

Input Design Process
1. Identify system inputs and review logical
requirements.
2. Select appropriate GUI controls.
3. Design, validate and test inputs using some
combination of:
a) Layout tools (e.g., hand sketches, spacing charts, or
CASE tools.
b) Prototyping tools (e.g., spreadsheet, PC DBMS, 4GL)
4. As necessary, design source documents.

A Logical Data Structure for Input Requirements
ORDER = ORDER NUMBER
+ ORDER DATE
+ CUSTOMER NUMBER
+ CUSTOMER NAME
+ CUSTOMER SHIPPING ADDRESS = ADDRESS >
+ ( CUSTOMER BILLING ADDRESS = ADDRESS > )
+ 1 { PRODUCT NUMBER +
QUANTITY ORDERED } n
+ ( DEFAULT CREDIT CARD NUMBER )
ADDRESS = ( POST OFFICE BOX NUMBER )
+ STREET ADDRESS
+ CITY
+ STATE
+ POSTAL ZONE

• It may be useful to walk through this technique for
specifying “logical” output requirements.
• The red and blue symbols are relational operators, that
is, they specify the relationship between attributes to be
included in the output in terms of
• Sequence +
• Selection [ data attributes]
• Iteration min { data attributes } max
• Optionality ( data attributes)
• Many CASE tools support this logical notation.

Input Prototype for Video Title Maintenance

Input Prototype for Member Order

Input Prototype for Member Shopping

Input Prototype for Web Shopping Cart

Input Prototype for Web Interface

Design of input

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