[Sigia-l] Card Sorting: How Many Users to Test

[Boniface Lau]

> From: Eric Scheid
> 
> ahh ... surely there's something controversial in Jakob's 
> latest AlertBox...
> 
>
> http://www.useit.com/alertbox/20040719.html
>
> > You must test fifteen users to reach a correlation of 0.90, which
> > is a more comfortable place to stop. After fifteen users,
> > diminishing returns set in and correlations increase very little:
> > testing thirty people gives a correlation of 0.95 -- certainly
> > better, but usually not worth twice the money. There are hardly
> > any improvements from going beyond thirty users: you have to test
> > sixty people to reach 0.98, and doing so is definitely wasteful.

Why did you think the above was controversial?


Boniface