why-you-only-need-to-test-with-5-users Jakob Neilsen

In the late 90s Jakob Nielsen and Tom Landauer established 80% of usability issues could be identified by 5 users. So a day of usability testing, 5×1 hour sessions, has the potential to dramatically improve a site’s usability, and so it’s efficacy with achieving both user and business objectives.

To realise this, Nielsen devised Discount Usability Testing: a lite methodology that encourages participants to speak their thoughts aloud as they go about using a website to accomplish tasks. It can be performed relatively easily and with few resources, so fits well with the maxims “Test early and often” and, from Agile, “fail early, fail fast”.
It’s simple format can also help product teams engage with research.

There are of course caveats: Rolf Molich who worked with Nielsen in 1995 to define the heuristics used in expert inspections, here highlights how the findings from small samples can vary dramatically.

Larsen cartoon about phones not being designed for hoofed creatures

Something else to mention is that research needs to be planned i.e. described in a test plan that will define scope, practical considerations and integration with other research etc.

In a series of posts I’d like to explore how to –

– practical tips for Discount Usability Testing.


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