8.1 interface design ims9001 - systems analysis and design
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8.1
INTERFACE DESIGN
IMS9001 - Systems Analysis and Design
8.2
Human–Computer Interface Design
The interface is the link between the users and the computer
end user
direct user
INTERFACE
INTERFACE
ProgramsProgramsDatabase
To many users, the interface is the system
8.3
The process of defining the manner in which humans and computers exchange information
Analogous to a conversation between 2 people Interface and dialogue design is critical for
successful information systems “...to the user the interface is the system” Should provide a uniform structure for finding,
viewing, and invoking different components of an information system
Designing Interfaces and Dialogues
8.4
Form and report design are key ingredients for successful information systems - especially for users
Each input data flow to a process will be associated with a form
Each output data flow from a process will be associated with either a form or a report
Forms and reports can be paper-based or screen-based
Inputs and Outputs: Forms and Reports
8.5
FORM is a business document containing some predefined data and also some areas for other data to be filled in typically based on one database record turnaround document is produced by a system
and then returned with input data REPORT is a business document that
contains only predefined data - a passive document for reading typically contains data from many different
database records
Forms and Reports
8.6
1. Collect initial requirements who will use the form or report what is its purpose when is it needed or used where does it need to be delivered how many people need to use it
2. Construct initial prototype 3. Users review and evaluate
prototype Iterate
Designing Forms and Reports
8.7
Narrative overview Form name, users, task, system, environment
Sample design Testing and usability assessment
user ratings on perceptions of usability dimensions - consistency, sufficiency, accuracy, etc
testing objectives, procedures and results- time to learn, speed of performance, rate of errors,
retention over time, user satisfaction and other perceptions
See Fig 13.4 p 438 and Fig 14.2 p 462 in Hoffer et al (2002)
Design Specifications
8.8
General guidelines: Meaningful titles
clear and specific, revision-no, date
Meaningful information needed and useable information
Balanced layout spacing, margins, balanced and clearly labelled
Easy navigation easy forward/backward moves, current position clear
Formatting Forms and Reports
8.9
TEACHING RESOURCE INFORMATION
BORROWER NUMBER 7712255BORROWER NAME DR. JIM SMITHLOAN NUMBER 12753DUE DATE 30-5-98ITEM CODE KS H1ITEM AVAILABILITY YESREQUIRED ITEM YESITEM CODE -ITEM AVAILABILITY -REQUIRED ITEM -ITEM CODE -ITEM AVAILABILITY -REQUIRED ITEM -CONFIRMED? NO
VagueTitle
Difficult to read,
InformationPacked tightly
No navigationinformation
No use of different intensity, fonts etc.
Poor Form Design
8.10
ClearTitle
Easy to read,Clear
balanced layout
Intensity differences,boxing, font
sizes
Clear navigationinformation
Good Form Design
8.11
Blinking and audible tones Colour, intensity, size and font differences Reverse video Boxing Underlining Capital letters Offsetting
Highlighting Information
8.12
Benefits of colour strikes the eye, draws attention to warnings accents an uninteresting display facilitates discrimination
Problems with colour colour blindness/eye strain resolution may degrade printing or conversion to other media may
not easily translate
Colour vs No Colour
8.13
Case display text in mixed upper and lower case
Spacing double spacing if possible, leave line between
paragraphs Justification
left justify with ragged right margin Hyphenation
do not hyphenate words between lines Abbreviations
use only when widely understood
Displaying Text
8.14
HELP SCREEN H2356ADD A FORM WITHIN A REPORTIN THE DATABASE WINDOW, CLICK THE FORM THAT IS BOUNDTO THE TABLE ON THE MANY SIDE OF THE ONT TO MANY RELATIONSHIP AND HOLD DOWN THE MOUSE BUTTON.DRAG THE FORM INSIDE THE MAIN FORM, AND THEN RELEASE THE MOUSE BUTTON.MICROSOFT ACCESS INSERTS THE SECOND FORM AS ASUBFORM WITHIN THE MAIN FORM.IF YOU NEED TO YOU CAN PRESS F1 T ORETURN TO THE MAINMENU, F2 TO GO TO THE PREVIOIS CARD AND F3 TO GO TO THENEXT CARD.
Vaguetitle
Fixed, upper
case textSingle
spacing
Poor Text Design
8.15
Cleartitle
Mixedcase
Spacing between sections
Clear navigationinformation
Good Text Design
8.16
Use meaningful labels for all rows and columns; relabel after change of
page Formatting columns, rows and text
sort in meaningful order place blank row after every 5 lines in long columns be consistent with typefaces and fonts
Formatting numeric, textual and alphanumeric data right justify numeric data, left justify textual data
Designing Tables and Lists
8.17
Clear separate column labels
Numeric dataRight justified
Good Table Design
8.18
3 major steps: 1 Designing the dialogue sequence
based on how the user wishes to use the system 2 Build a prototype
use tools such as CASE tools, Visual Basic, Access 3 Assess Usability
use same approach as with forms and reports - time to learn,speed of performance, rate of errors, retention over time, subjective satisfaction
Design specification can be completed as for forms and reports
Designing Dialogues
8.19
Common interface methods are:
Command language interaction
Menu interaction
Form interaction
Icon/object-based interaction
Interaction Methods and Devices
8.20
Users enter explicit commands to invoke operations users must therefore remember syntax and
semantics MSDOS, UNIX commands
copy A:myfile.doc to B:myfile.doc Complex applications such as word processors
and spreadsheets may have many commands <CTRL-P> print <CTRL-S> save <CTRL-C> copy
Command Language Interaction
8.21
Users select from a list of system options and a specific operation is executed
Menu interaction is still the most widely used interaction method
Menus can differ greatly in their design and capability
simple single menu hierarchy of menus pop-up menus drop-down menus graphic menus
Menu Interaction
8.22
TEXT-BASED SYSTEM MENU OF CHOICES ----------------------------
1 BOOKINGS2 CUSTOMERS3 TOURS4 MAINTENANCE5 LOGOUT
What’s wrong with this one?
Simple Single Menu
8.23
MainMenu
Menu Hierarchy
8.24
Wording meaningful title, clear, unambiguous command verbs
Organisation consistent, eg. related options should be grouped
together Length
use sub-menus to break up very long menus Selection
methods should be clear and consistent Highlighting
should be minimised and used to convey selected options (marked) or unavailable options (dimmed)
Guidelines for Menu Design
8.25
Users fill in ‘blanks’ on a form when they interact with the system
Screen format is similar to paper-based forms Effective for both input and presentation of
data Form interaction is common on many
applications, the World Wide Web Form-based programming languages
VB, Delphi, CGI(?)
Form Interaction
8.26
Often based on metaphor Icons are graphic symbols that look like
the processing option they represent Operations are selected by pointing at
and clicking on the desired option Easily understood and take up little
screen space Many icons appear in the form of
buttons or controls
Icon/Object-Based Interaction
8.27
Keyboard Mouse Joystick Trackball Touch screen Light pen Graphics tablet Voice
Common Interaction Devices
8.28
Entry never require data to be inserted that is already known
Defaults always provide defaults where appropriate
Format provide format details (decimal points, dollar signs, dates ...)
Provide help for help, concepts, procedures, messages, menus, function keys,
commands, etc. Validation tests are usually handled by DBMS or by programs:
Type proper type of data (eg. numeric, alpha …)
Combinations do values in several fields combine in a sensible way
Missing data eg. must have quantity for each customer order
Structuring and Validation of Data Entry
8.29
Interface Design Principles
Five principles: Support “Transportability of
Knowledge” Be Consistent Provide Feedback Use Drab Colours Make the User Boss
8.30
Transportability of Knowledge
Make use of what the user already knows eg File>Exit quits Windows applications
Answers lots of design questions for you What are menus? - things that drop down
from the top What’s the first menu option? - File What’s the last menu option? - Help What does the word exit mean? - quit the
application.
8.31
Be Consistent
Always do the same thing in the same way it’s always Exit Exit only means “Leave this application” Exit never means “Go back to the previous
screen.” or “Go back to the splash screen.”
The (Drop-Down) Menus are always the same. If menu options are inappropriate in particular
locations, dim them.
The words you use to refer to objects are the same across screens.
8.32
Transportability and Consistency Work Together
Any exception means: The user always has to stop and think:
“Is this the exception?” “Do I have to think twice about this one?”
So any breakdown in consistency or transportability means: The user is slowed down The user is frustrated The user makes more mistakes
8.33
Consistency in Appearance and Performance
These aren’t the same. You can see inconsistency in appearance but not
in performance How (and when) does your system respond to an
input error? When do you prompt the users? How does the user access the Help system?
(i.e., does [F1] always work?) How must the user enter dates, percentages,
etc. ? Where do forms appear on the screen?
8.34
Provide Feedback
Feedback Lets the User Know What’s Going on
Examples A button goes down when you click it The mouse pointer turns into an hourglass while
short tasks run There’s a progress bar for long tasks
Objects always respond to actions on them. Something always shows you that it’s worked
Negative Example Fill in a form, click on the Save button Nothing happens……The user is left in doubt.
8.35
Use Drab Colours
Some colours cause problems eg red red seems dim, as very few cones in retina
sensitive to red 3D effect of red on green or green on red for
everyone red seems fuzzy around edges
Colour perception is personal What looks good to you won’t necessarily
look good to many others Drab colours are best
8.36
Make the User Boss
In traditional computer programs The program walks the user through a series of
steps The user has to perform these steps correctly and
in the required order The program (and programmer) knows in
advance what the user is doing at any time. The program and programmer are always in
control (and there’s always a known point, called the control point, moving through the program)
So traditional programmers speak of the “flow of control” through the program.
8.37
There’s No Point of Control
Control is passed to the user Within reason they can:
Do what they want in the order they want Enter partial and incomplete data Stop in the middle of a task Leave blank and incorrect data on the screen
for awhile
The computer program is passive The user is active The user becomes the boss
8.38
Mechanisms to control user access include views
particular users see subset of DB in the interface
authorisation rules restrictions to access and actions on data
encryption procedures encryption and decoding procedures are necessary
for highly sensitive data
authentication schemes access restrictions controlled by passwords,
biometric devices and smart cards
Controlling User Access
8.39
Usability typically refers to speed - efficient completion of task accuracy - output provides what is expected satisfaction - output is liked
Design guidelines for usability Consistency - of operation Efficiency - related to user task Ease - output self explanatory Format - consistent format between entry and display Flexibility - must be convenient to user
Assessing Usability
8.40
User experience, skills, motivation, education, personality
Task time pressures, costs of errors, work duration (fatigue)
Systems platform will influence interaction styles and devices
Environment social issues and role should be considered
Contextual Issues
8.41
Measures of usability Time to learn Speed of performance Rate of errors Retention over time Subjective satisfaction
Usability data can be collected by observation interviews keystroke capturing questionnaires
Measuring Usability and Collecting Usability Data
8.42
References
HOFFER, J.A., GEORGE, J.F. and VALACICH (2005) Modern Systems Analysis and Design, (4th edition), Pearson Education Inc., Upper Saddle River, New Jersey, USA. Chapters 11, 12
WHITTEN, J.L., BENTLEY, L.D. and DITTMAN, K.C. (2001) 5th ed., Systems Analysis and Design Methods, Irwin/McGraw-HilI, New York, NY. Chapter 15