Computer Science Honours 2011
Meet users expectationsp1. Match the real world2. Consistency & standards3 Help & documentation3. Help & documentation
User is boss4. User control & freedom
Vi ibilit f t t t5. Visibility of system status6. Flexibility & efficiency
Errors7. Error prevention8. Recognition, not recall9. Error reporting, diagnosis, and recovery9. Error reporting, diagnosis, and recovery
Keep it simple10. 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/designersdevelopers/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 evaluatorsp different evaluators find different
problems the more the better, but diminishing
returnsreturns 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 systemD 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 detailsO 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
blproblems
Used to uncover how people p porganize 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 organizeorganize
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 milkMilks
Cheddar cheese
Drinking yoghurt
Skim milk
Full cream milk
Skim milk
Drinking yoghurt
Cheddar cheeseCheese
DairyGouda cheese
Blue cheese
Cheddar cheese
Gouda cheese
Blue cheese
Full cream milk
Bulgarian yoghurt Drinking yoghurtYoghurts
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
Optimalsort.com or websort.net