Computer Science Honours 2011
Meet users expectations p
1. Match the real world
2. Consistency & standards
3 Help & documentation
3. Help & documentation
User is boss
4. User control & freedom Vi ibilit f t t t
5. Visibility of system status
6. Flexibility & efficiency
Errors
7. Error prevention
8. Recognition, not recall
9. Error reporting, diagnosis, and recovery
9. Error reporting, diagnosis, and recovery
Keep it simple
10. Aesthetic & minimalist design
Usability inspection method
Cost‐benefit ratio is good
f d b b l
Performed by a usability expert
Steps:
inspect UI thoroughly
compare UI against heuristics
lists usability problems found
▪ Explain & justify each problem with heuristics
http://www.id-book.com/catherb/
Justify every problem with a heuristic
Justify every problem with a heuristic
“too many choices on the home page (Aesthetic & Minimalist Design)”
can’t just say “I don’t like the layout”
List every problem
List every problem
even if an interface element has multiple problems
Go through the interface at least twice
once to get the feel of the systemg y
again to focus on particular interface elements
Don’t limit yourself to the 10 heuristics
we’ve seen others: affordances, visibility, Fitts’ Law, visual variable, l i i l l i i l
gestalt principles, colour principles etc
but the 10 heuristics are easier to compare against
E l i h i h
Evaluator is not the user either
maybe closer to being a typical user than the developers/designers
developers/designers
don’t know system model
Heuristic evaluation finds problems that user Heuristic evaluation finds problems that user testing often misses
inconsistent fonts
Fitts’ Law problems
But user testing is the gold standard for
usability
Use multiple evaluators p
different evaluators find different problems
the more the better, but diminishing returns
returns
Nielsen recommends 3‐5 evaluators
Alternate heuristic evaluation with user testing
each method finds different problems
heuristic evaluation is cheaper
It’s OK for observer to help evaluator
as long as the problem has already been
as long as the problem has already been noted
this wouldn’t be OK in a user test
l k
Heuristic evaluation works on:
sketches
t t
paper prototypes
buggy implementations
“Missing‐element” problems are harder to find on Missing element problems are harder to find on sketches
because you’re not actually using the interface, you aren’t blocked by feature’s absence
look harder for them
A th bilit i ti th d
Another usability inspection method
Focuses on how easy it is for new users to accomplish tasks with the system
D i t t f th d i & i
Designer presents an aspect of the design & usage scenarios
Expert is told the assumptions about user population, context of use, task details
O f t lk th h th d i t t ith
One of more experts walk through the design prototype with the scenario
Experts are guided by 3 questions
Will the correct action be sufficiently evident to the
1.
Will the correct action be sufficiently evident to the user?
does the user understand that this subtask is needed to h th ' l?
reach the user's goal?
2.
Will the user notice that the correct action is available?
e.g. is the button visible?
3.
Will the user associate and interpret the response from the action correctly?
will the user know that they have done the right thing after performing the action?
As the experts work through the scenario they note bl
problems
Used to uncover how people p p
organize information and how they categorize and relate concepts
Create usable information structures ( h ) h i
(such a menus) that saves users time
Words on the cards reflect the
names of the things that you want to organize
organize
Sections, terms, menu items,
images, individual window/pages
Users sort them into groups label
Users sort them into groups label groups
Low fat milk
Low fat milk
Milks
Cheddar cheese Drinking yoghurt
Skim milk Full cream milk
Skim milk
Drinking yoghurt
Cheddar cheese
Cheese
Dairy Gouda cheese
Blue cheese
Cheddar cheese Gouda cheese
Blue cheese
Full cream milk
Bulgarian yoghurt Drinking yoghurt
Yoghurts
Bulgarian yoghurt g y g
Bulgarian yoghurt
I f l
Informal way:
manual
l k f d i h l
look for trends in the clusters
Formal way:
cluster analysis statistics nontrivial
cluster analysis – statistics – nontrivial
takes groups created by users and produces tree graphs showing relationships between groups of graphs showing relationships between groups of cards
