Topic
Metrics
Sooner or later someone wants a number. Metrics are how you turn 'does it work?' into something you can track and argue with - but a figure is only as honest as the thing it counts, and a tidy dashboard can hide as much as it shows.
This cluster covers the numbers UX leans on - how long a task takes, how many people make it through - and, just as importantly, what they leave out. A metric ticking upward is not the same as a person who is better off.
Each entry shows the measure being taken and then poked at, so you can see both what it tells you and where it quietly lies.
The metrics entries 10
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metrics
Time on task
Time on task is how long it takes someone to complete a specific task, from start to finish. It's the most common efficiency metric in usability testing - and one of the easiest to misread.
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metrics
Conversion rate
Conversion rate is the share of people who complete a goal - buy, sign up, subscribe - out of everyone who could have. It's usually quoted end to end, but it's really the product of every step's survival rate along the way.
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metrics
Task success rate
Task success rate is the share of people who finish a task - four of five users complete it, so 80%. It is the most basic measure of whether a thing works at all, and the easiest to read too much into.
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metrics
Net promoter score
Net promoter score asks one question - "how likely are you to recommend us?" on a 0 to 10 scale - then subtracts the share of detractors (0 to 6) from the share of promoters (9 to 10). The 7s and 8s sit in the middle as a neutral zero. The result runs from -100 to +100.
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metrics
CSAT (customer satisfaction score)
CSAT - customer satisfaction score - asks people to rate their satisfaction, usually on a short scale, right after an experience, and reports the percentage who answered positively (typically the top one or two ratings). It's a quick, intuitive read on "did that go well?" for a specific interaction - a purchase, a support chat, a feature.
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metrics
Customer effort score (CES)
Customer effort score (CES) asks one thing after an interaction: how easy was it to get what you needed? Usually a single agree-scale statement ("the company made it easy to handle my issue"), it shifts the question from "are you delighted?" to "did we get out of your way?" - on the theory that reducing effort keeps people more reliably than trying to wow them.
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metrics
Bounce rate
Bounce rate is the share of visits where someone lands on a page and leaves without any further interaction - one page, no second click. It's easy to measure and easy to misread: a high bounce rate can mean people couldn't find what they wanted, or that they found it instantly and left satisfied. The number means nothing until you know what the page was for.
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metrics
Error rate
Error rate is how often people make errors while doing a task - mistakes per attempt, or the share of attempts that go wrong. It's a usability metric, not a verdict on users: a high error rate almost always points at a confusing design, not careless people, and the type of error tells you what kind of fix it needs.
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metrics
HEART framework
HEART is Google's framework for measuring user experience across five dimensions - Happiness, Engagement, Adoption, Retention and Task success - so you capture quality of experience, not just business output. Its real engine is the "Goals-Signals-Metrics" process that turns each fuzzy dimension into a concrete number, forcing you to decide what success means before you pick what to count.
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metrics
System usability scale
The system usability scale is a short questionnaire with ten statements rated from strongly disagree to strongly agree. It converts how usable something feels into a single score from 0 to 100. It’s quick, standardised, and surprisingly comparable across very different products.
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Know these already? Take the metrics quiz, or revise the terms with flashcards.