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

[Jonathan Baker-Bates]

> > You must test fifteen users to reach a correlation of 0.90, 

I'm unclear how these correlations square with the "who to test" issue.
Most clients have desired segments they want represented in their
testing (Teens, Housewives, Bald Women... OK maybe not that divergent,
but sub-sections of their customer base), so is he talking about the
number of users you have in the *same* segment here? If in a test group
of 20, the Asian Doctors group things radically differently from the
Truck Drivers and Tea Ladies, surely the fact that there are only five
Asian Doctors is significant.

Jonathan

 

> -----Original Message-----
> From: sigia-l-admin at asis.org [mailto:sigia-l-admin at asis.org] 
> On Behalf Of Eric Scheid
> Sent: 19 July 2004 12:36
> To: sigia l
> Subject: [Sigia-l] Card Sorting: How Many Users to Test
> 
> 
> 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.
> 
> 
> ------------
> When replying, please *trim your post* as much as possible.
> *Plain text, please; NO Attachments
> 
> Searchable list archive:   http://www.info-arch.org/lists/sigia-l/
> ________________________________________
> Sigia-l mailing list -- post to: Sigia-l at asis.org Changes to 
> subscription: http://mail.asis.org/mailman/listinfo/sigia-l
> 

_________________________________________________________________________________________________________________________
Internet communications are not secure and therefore Oyster Partners Ltd does not accept legal responsibility for the contents of this message. Any views or opinions presented are solely those of the author and do not necessarily represent those of Oyster Partners Ltd.