Elaborate usability tests are a waste of resources. The best results come from testing no more
than 5 users and running as many small tests as you can afford.
How many users you need
Don’t mind taking medications
I have an obligation to take
good care of this kidney
I do not have any influence on things going wrong; I will
do the best I can.
Concerned and careful
I do not want to blame myself for ruining
You have to follow the rules.
I do not feel sick; not everybody knows I have a kidney
transplant. I want to do things without thinking about my
Negative towards medications
This kidney is from my mum and that is special to me, but
I am not extra careful with my kidney because it is from
- Do people understand our product?
- Do they care?
- Can they ﬁgure out how to use it?
- Which messages are most eﬀective at explaining it?
Validating prototype with users
(of usability sessions)
• ask to speak out loud (repeat if a user forgets)
• ask what this screen is about, what they can do there
• ask to “guess” what will happen if… (they press a
• ask how it could be improved
• ensure that there is no right or wrong answers
(of usability sessions)
• don’t advocate for your design/solution
• don’t blame them if they make a wrong guess
• don’t argue!
Missed rate per active user / week
Retention rate per user / week
Activation rate per user / week
Happiness: User attitudes, often collected by a survey.
Engagement: Frequency, intensity or depth of interaction.
Adoption: Gaining new users of a product or feature
Retention: The rate at which existing users are returning.
Task completion: Efﬁciency, effectiveness and error rate.
by Kerry Rodden
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Simpliﬁed on-boarding and improve adherence metrics
Changes based on usage data
• Understand the product and reveal problems
• Emphasize with the user
• Reveal tech constraints
• Understand business goals
• Deﬁne goals for re-design
• Deﬁne metrics
Ideation & Prototyping
Validation & Iteration
• When do you use it? What did you buy / do you usually buy at [each time]? (breakfast,
morning snack, lunch, afternoon snack, dinner)
• Can you tell me why you picked [item]? (repeat per item)
• What criteria goes into selecting what you want to eat?
• What is your usual lunch routine?
• Where do you go? What do you eat there? Why?
• Imagine this is a magic wand, you could get any improvement you want.