Post on 26-Dec-2015
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Learning Objectives To become familiar with the various
common methods by which end users interact with IS
To review the common computer input devices and to explore the newer, more sophisticated input technologies
To understand the three basic metaphors for designing human–computer interaction mechanisms
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Learning Objectives To understand and be able to
apply the basic design guidelines for high quality and usable data entry screens
To understand the two categories of input controls, as well as their strengths and limitations
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User Interface Methods Command Dialogue Menus Icons and Buttons Input Screens and Forms Natural Language Recognition
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Command Dialogue End users initiate all dialogue by
issuing instructions to the computer via a structured syntax of command
Requires a significant learning curve on the part of the end user
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Menus Present the end user with a list of
available alternatives Types of menus
Single menu approach Hierarchical menu approach Menu bar approach Pop-up menu
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Icons and Buttons End user selects and executes
commands by pointing and clicking at graphical buttons or icons
Easy recognition by end users
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Input Screens and Forms Use a screen-based form to get
input from users The navigation method should
allow the user to move from field to field in a logical, intuitive sequence
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Figure 12-3. Examples of Logical and Counterintuitive Navigation Sequences
Proper navigation Poor navigation
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Voice Recognition Uses voice synthesis technology Allows the user to interface with
the computer device by using natural language and voice commands
Error rate is decreasing in recent years
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Voice Recognition Future development
Computer scientists looking for pauses in our voice
Speaker independence Understanding of gesture
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Voice Recognition Natural Computing
Adapt to natural human interaction skills
To interpret vocal command To track movement and gestures
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Common Input Device Punch Card Biometric Input Devices
Automatic identification of a person based on his or her physiological or behavioral characteristics
Pattern recognition system
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Common Input Device Optical Input Devices
Barcode Provide a simple and easy method of
encoding text and numerical information to be read by inexpensive devices
A series of parallel, adjacent bars and spaces
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Common Input Device Optical Input Devices
OMR Optical Mark Reading Uses an array of light-emitting diodes
(LEDs) to scan for marks in certain position
Used for questionnaires, tests, voter registration, market research
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Figure 12-6. Optical Mark Reader Scan Sheet and Auto-Scanner
Skunk Marks
Data Scanning
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Common Input Device Optical Input Devices
OCR Optical Character Recognition Scan virtually any form or document
containing numbers, letters, or marks
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Common Input Device Smart Card
A plastic card embedded with an integrated circuit chip
Used for payment processing, identification, network computing, health care management
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Guidelines for Input and Interface Design
HCI Metaphors Desktop or direct manipulation Document Dialogue
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The Desktop Metaphor Build on the common set of
activities and organizational schemes associated with a common desktop
Create an electronic desktop that provides all of the flexibility and advantages of a physical desktop
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The Document Metaphor The end user interacts with the
computer by browsing through, or entering data in electronic documents and forms
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The Document Metaphor Hypermedia
Links graphics, video, and audio together in a manner that allows the users to easily navigate between the documents
Hyperlinks bear a strong resemblance to reference in paper documents
Filling in forms on web pages is reminiscent of filling in paper forms
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The Document Metaphor Disadvantages of desktops
Do not provide mobility Are not spatial Vary in software
Reading machines Encapsulate the physical aspects we
are accustomed to when reading from a hard copy
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The Dialogue Metaphor Attempt to create an electronic
version of a conversation using natural language
Electronic Personal Assistant
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Data Entry Issue Consistency
The methods and functions available on one data entry screen should be consistently applied to all entry screens
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Data Entry Issue Standardized Interface
Learning curve for an end user is significantly reduced
The probability of data entry error across screens is reduced
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Capability Category Examples Cursor Control
Moving the cursor forward or backward
to allowable data fields. Directly moving the cursor to the first or
last field on the screen. Move the cursor forward or backward by
one character within a data field.
Editing
Delete the previous character. Delete the current character. Delete the entire field entry. Clear the entire form of data.
Exiting
Commit the data on the screen to the
database or application program. Navigate to a new screen or form. Confirm recent data entry before moving
to another screen or form.
End User Help
Obtain help with a particular data field
definition or entry. Obtain help on the purpose and
limitation associated with a particular data entry screen.
Table 12-1. Common Data Entry Screen Functions
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Data Entry Activity
Guideline for Effective Design
Data Entry
Avoid requiring entry of data that can be computed, derived, or retrieved from an existing on-line source.
Field Defaults
Provide relevant field value defaults where appropriate. (i.e. assume current date for invoice date field)
Required Units
Clearly indicate the desired unit values for data entry fields. (i.e. pounds, inches, dollars, tons, etc.)
Data Replacement
Provide “intelligent character replacement functions by suggesting a completed entry after the user has typed the first few characters.
Field Captions
Provide information field captions such that the end user can determine the appropriate data to enter.
Field Formatting
Provide explicit formatting examples where relevant to indicate the proper method for entering data with required embedded symbols or a specific sequence. (i.e. social security number, 999-99-9999 or date, mm/dd/yyyy)
Data Alignment
Provide automatic alignment for data entries using left justification for text and right-justification or decimal justification for numbers.
End User Help
Wherever possible, provide context-sensitive help mechanisms and hot-key access to help facilities.
Table 12-2. Guidelines for Effective Input Screen Design
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Data Entry Screen Characteristics
Determine default value when appropriate
Include context-sensitive help Pop-up help, hotspots, tool tips, etc.
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Providing User Feedback System Status Feedback
Users needs to be reassured that the intended process is successfully executing
Users need some indication of the estimated length of time for the process to execute or complete
System status indicator
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Providing User Feedback User prompts
The designer needs to communicate information to the user in the form of a statement or a selection that is related to either a process in progress or a possible error condition in effect
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Dialogue Design Usability Assessment
Used to determine the effectiveness and efficiency of the various interface structures and components of the application
Surveys, questionnaires, focus groups, field observation
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Dialogue Guideline
Explanation
Be consistent
All dialogues should be consistent in action, sequence, required keystrokes, and terminology.
Enable user shortcuts
End users should be allowed to take advantage of shortcut keys or macro commands wherever possible and appropriate.
Provide relevant feedback
Feedback should be provided to the end user for every data entry action.
Allow for closure
All dialogues should have a clear beginning, middle, and end.
Provide error-handling guidance
All possible errors should be captured by the system and reported back to the end user in a manner that allows for correction or provides suggestions as to how to proceed.
Allow reversal of action
Wherever possible, end user actions should be reversible and data deletion should not occur without explicit confirmation from the end user.
Provide user control
The dialogue should allow experienced users to feel in control of the system and should facilitate inexperienced end users by allowing the user to take greater control of the process as experience develops.
Reduce cognitive load
Dialogues must be simple to use and must provide for a minimum cognitive load on the end user.
Table 12-3. Guidelines for the Design of Effective HCI Dialogues
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Designing the Input Controls Intended to ensure that the data
input to the system are both accurate and valid to the highest degree possible Access Control Data Control
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Designing the Input Controls Data Control
Appending error Truncation error Transcription error Transposition error
Design Control Mechanism Table 12-4
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Input Control Mechanism
Explanation
Data Typing Data should be checked for proper type (numeric, alphabetic, or alphanumeric)
Reasonableness Data should be tested for reasonableness of value given the situation (negative interest rates not allowed, appropriate rate of pay for specific employee category)
Expected Value Data should be checked against some expected value where appropriate (model of automobile should match make of automobile)
Missing or Required Data
Fields should be checked and flagged for missing data that is deemed necessary to complete the data entry process ( has a quantity been provided for every item on the purchase order?)
Check-Digit Calculation
Check digit calculation should be conducted upon appropriate field entry to insure proper account number or other numerical data accuracy.
Data Format Data should be checked against any required format or template to insure proper entry (999-99-9999, (999) 999-9999, 99AAXX9AX)
Value Range Data should be checked against any known or established value range (two-letter state codes should come from acceptable list of codes)
Entry Size The number of expected characters should be checked where appropriate (is the social security number exactly nine digits?)
Allowable Entry Data should be limited to a range of allowable entries and this range of choices should be provided to the end user, where appropriate)
Table 12-4. Input Validation Control Mechanisms
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Process Example Number each digit of a numeric entry according to place value from either right or left beginning with 2.
Assume account number of 34763:
34763 23456
Multiply each digit in the numeric entry by its assigned place value.
3 4 7 6 3 x 2 3 4 5 6 6 12 28 30 18
Sum the result of the multiplications.
6 + 12 + 28 + 30 + 18 = 94
Divide the sum by the modulus number (usually 10 or 11)
Assume a modulus number of 11:
94 / 11 = 8 remainder 6
Subtract remainder from modulus number and append check digit to numerical entry.
11 – 6 = 5 (check digit)
347635
Table 12-5. Check Digit Calculation Method
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Designing the Input Controls Access Control
Authentic Mechanism Authorization Schema Encryption Mechanism
- End -
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Chapter Summary This and the previous chapter
provided a detailed overview of the design and control issues on system input and output. With these two tasks complete, the system is well on its way to completion and implementation.