[Sigia-l] Cluster analysis is dead - was Jakob wrong?

[Miguel Arroz]

Hi!

   This discussion interests me, as I am also writing a Card Sorting 
software, for Mac OS X. I want to state that I have little experiencie 
with card sorting. I'm doing this because I work with some people that 
belong to the Web-Design department of my college, and they said a Card 
Sorting software for Mac was much needed.

   1) When a similarity matrix is constructed, the process that creates 
the
> matrix only captures information about cards that were grouped 
> together.
> If a person in the test decides they want to nest some cards below some
> others,
> the parent child information is lost in the matrix construction.  That
> makes
> the technique blind to the test subjects card hierarchies.

   In every description of Card Sorting method I read, I found no 
reference to hierarchys. As far as I understand, people should only 
make "flat" clusters (or groups, as I like to call them) of cards. I 
guess that's because hierarchy would be too complex for many people to 
deal with (card sorting MUST be an easy exercise for the "sorters", or 
they will not provide good results).

   The designer must read the exerice results, and if he feels that way, 
he may take a group, and make a second card-sort exercise with only 
that group, to see how people would classify the cards inside that same 
group, making sub-groups. Sorry for my poor english...

> 2) The similarity matrix and resulting clusters represent an average.
> The card sorts may capture more than one fundamental 'mode', for 
> example
> the top level classifications could be year versus genre in a card sort
> about movies.  If the modes are fundamentally opposed, such as year vs
> genre, then the kind of average you would get out of cluster analysis
> with all the sorts included could be a non representative average, ie
> junk."

   Hum... that only depends on the "treshhold" the dedigner defines, 
while looking to the dendogram. If the designer sees that there are two 
ways people organized the cards with about 50% each, he should be smart 
enough to drop the treshold to about 40%... remember that Card Sorting 
software is just a tool to let the designer analyze the patterns more 
easely, and not a "magic" tool that says how the site should be 
organized.

   Yours

Miguel Arroz

       "I felt like putting a bullet between
        the eyes of every Panda that wouldn't
        scr*w to save its species."       -- Fight Club

   Miguel Arroz - arroz at guiamac.com - http://www.guiamac.com