Website Development: Why 5 Is The Magic Number

Kenny Jahng —  2011/11/21 — 3 Comments

Whenever an organization sets out to tinker with the website to improve it, or even go for the complete revamping of the site, it’s based on some feedback that the site isn’t doing what is intending to do.  This can be based on internal feedback, implicit or explicit comments from site visitors, a gut feeling that the site can communicate better, or the plain facts that your site conversion goals aren’t happening.

So what happens next?  Most often than not, a group of people go into meetings and set about reconfiguring the site structure, improve navigation, updating the aesthetics to reflect current Web 2.0 and beyond trends, and revising the content.   Hopefully they do it in a way that is strategic in nature or bring in someone that can help with that.

But whatever the process, when you finally flip the switch, only the actual usage by site visitors can tell you whether you succeeded or not.

Here’s the part where most groups drop the ball.  One of the most critical milestones in site development happens right here — not before when you’re whiteboarding the site and its contents.  This is where you need to do some usability testing.   Qualitative and quantitative research will guide you on what works and what doesn’t.

But because focus groups and user testing seems so sophisticated and enigmatic, most site owners don’t ever go through with the steps that can radically impact how your message is received by the visitors coming to your site.  The superficial pushback on this area seems to be in two immediate areas beyond the lack of comfort / knowledge for how to preceed:

(1) We don’t have money for that!  Testing dozens and dozens of people would cost more than we can afford.

(2) We don’t have the time for rounds of user testing.  That would delay our website project too much, or we have so much other stuff to do now that we’ve finished the website revamping.

But here’s the kicker, it doesn’t have to be expensive nor time-consuming to get the critical feedback you need to communicate better with your visitors.

And here is why 5 is the magic number in useability testing:

According to Jakob Neilson, the usability guru (seriously, you should check out his site,, the ideal scenario usually warrants 76 users for comprehensive quantitative testing that addresses the typical outliers that come through.  And a more manageable 15 users need to be tested in order to get at all the qualitative usability issues in the design of a site.

But in reality, the magic number is really 5.  That’s it.  FIVE people. . .


Jakob sums it up in this sentence for me:

The cost-benefit analysis of user testing provides the optimal ratio around three or five users, depending on the style of testing.


The other tip that goes along with this research is that you need to approach it as an iterative process.

It’s better plan for multiple tests of small batches.    Instead of getting the 15 people to give you absolute confidence in finding all usability problems with your site, he recommends that you rather do 3 rounds of testing 5 people with each update of the site.  This will get you much further along in the end.

So how do you do the actual tests?  His site and other places on the web can help inform that process.   I personally have been using a site called which allows me to set-up a task to test and offer it to multiple users.    I’ll share more about it in the next post.

It’s your turn to share: Have you ever done user testing on your site?  Have you ever participated in feedback testing?  Leave your answers in the comment section below.

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3 responses to Website Development: Why 5 Is The Magic Number

  1. Just doing one user test will make you a believer. Seriously, start with just one and see how you feel.

    I've been using a screen recording software combined with and google voice, but I like to make things difficult.

    Great tips! I like the line under the graph "The most striking truth of the curve is zero users give zero insights"

    • Thanks Tim for your comments. Your point about screen recording a Join.Me screen sharing session and a GoogleVoice call to record the audio is great because you don't have to use any paid service at all to get the same insights. And doesn't like free?!Yup, so many website owners are flying blind, guided only by their assumptions… When it is so easy to discover the useability problems keeping visitors from doing what you want them to do efficiently.Even one test will usually be enough to change your perspective in my opinion — validating some suspicions or things that you already know but are in denial(!), or bring up such amazingly different ways to look at your site that it leaves you scratching your head (and then wanting to do more tests).Onward with the tests!Kenny

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