Basic principles of Usable Interface Learnability, Efficiency, Memorability, Errors, Satisfaction Utility - does it what you need? How to improve Usability

1. BASICS OF
USABILITY
how easy is the interface to use

2. What is USABILITY?
how easy is the interface to use
Learnability
Efficiency Errors
SatisfactionMemorability
Usability is a QUALITY ATTRIBUTE that assesses
HOW EASY USER INTERFACES ARE TO USE.

3. Learnability
How easy is it for users to
accomplish basic tasks the
first time they encounter the design?
The user can QUICKLY GO from NOT KNOWING the
system to GETTING SOME WORK DONE with it.
ex: Can you find the “Pay Now” button even after a
couple of beers?

4. Efficiency
Once users have learned the design,
how quickly can they perform tasks?
Once the user has LEARNED THE SYSTEM, a high level of
PRODUCTIVITY is possible.
ex: Can grandad quickly find his favourite program on BBC
iPlayer that he listens to everyday?

5. Memorability
When users return to the design after a
period of not using it, how easily can
they reestablish proficiency?
EASY TO REMEMBER > The infrequent user is ABLE TO RETURN
to using the system AFTER SOME PERIOD of not having used it,
WITHOUT HAVING TO LEARN EVERYTHING ALL OVER.
ex: When you came back from your holiday, can you still navigate
Instagram pages as easily as you could before?

6. Errors
How many errors do users make, how
severe are these errors, and how easily
can they recover from the errors?
Users do not make many errors during the use of the system,
or if they do make errors they can easily recover from them.
Also, NO CATASTROPHIC ERRORS SHOULD OCCUR.
ex: Is mum still clicking on ‘Save’ when she wants to click
‘Publish’ on WordPress?

7. Satisfaction
How pleasant is it to use the design?
Pleasant to use: Users are subjectively SATISFIED
by using the system; THEY LIKE IT!
Ex: Does your uncle find the AirBNB website
confusing and clunky to use?

8. What is USABILITY?
USABILITY UTILITY
+ USEFUL
=key attribute - UTILITY refers to the design's functionality:
Does it do what users need?
It matters little that something IS EASY if it's NOT WHAT YOU
WANT.
It's also no good if the system can hypothetically DO WHAT
YOU WANT, but you CAN’T MAKE IT happen because the
user interface is TOO DIFFICULT.

9. Why is usability IMPORTANT?
On the Web, usability is a necessary
condition for survival
There are plenty of other websites available - leaving is the first line
of defense when users encounter a difficulty.
Game over - Customer lost
equipment damage
anger and frustration
higher error rates
physical and emotional injury
decreased productivity
costs money

10. How to IMPROVE usability?
1. Before starting the new design, test the old design to
identify the good parts that you should keep, and the bad
parts that give users trouble.
2. Test your competitors' designs to get cheap data on a range
of alternative interfaces that have similar features to yours.
3. Conduct a field study to see how users behave in their
natural habitat.
4. Inspect the design relative to established usability
guidelines whether from your own earlier studies or
published research.
5. Once you decide on and implement the final design, test it
again

11. Zdeněk Lanc
UX designer
web:
www.yd.cz
e-mail:
yd@yd.cz
twitter:
@ZdenekLanc
Thank you!