1- Learnability: the ease with which new users can begin
effective interaction and achieve maximum
performance
1.1 Predictability : it is means that the user’s knowledge of the
interaction history is sufficient to determine the result of future
interaction.(can I ‘tell’ what will happen based on what I have gone
through in past)
1.2 Familiarity : how prior knowledge from real world applies to new
system , The appearance of the object stimulates a familiarity with its
behavior (like a button on door & form) , Guessability
1.3 Generalizability : Applying specific interaction knowledge to new
situations like MS word & excel etc , Can be seen as a form of consistency ,
applications should offer the Cut/Copy/Paste operations whenever
possible
1.4 Consistency : Likeness in input - output behaviour arising
from similar operation , The user relies on a consistent
interface
2- Flexibility: the variety of ways the
user and system exchange
information
2.1 Dialogue initiative : Who controls dialouge. freedom from system
imposed constraints on input dialogue , a system-driven interaction
hinders flexibility whereas a user-driven interaction favours it , user
should be able to Cancel, suspend or resume tasks at any point .
2.2 Multithreading : ability of system to support user
interaction for more than one task at a time
2.4 Substitutivity : allowing equivalent values of input and
output that be substituted for each other , Ex : Margin settings
provide measurement in inches & centimetres
2.5 Customizability : Interface can be modified to different
needs ex : Colours & layout change, provide choice of
methods; allow short-cuts; permit users to change features:
deferred design
2.3 Task migratability : Transfer responsibility for task
execution between user and system like spell-checking.
3- Robustness: the level of support provided
to the user in determining successful
achievement and assessment of goal
3.1 Observability : ability of user to evaluate the internal
state of the system from its apparent representation
3.2 Recoverability : Support for Undoing errors , ability of user to
take corrective action once an error has been recognized , Error
messages should be concise, informative, Specific & constructive
3.4 Task conformance/Completeness : degree to
which system services support user's tasks , System
should perform all the tasks that user needs or
wants
3.3 Responsiveness : Measures the rate of
communication between the system and user , Response
time is generally defined as the duration of time needed
by the system to express state changes to the user, short
durations and immediate response times are desirable