[Sigia-l] in need of quotes

[Chang Su]

Hi, I am looking for two quotes related to IA.
1) how many top-level categories on a web site is best? Here I want to
know the range of the 1st level topics on a taxonomy developed for a
complicated domain.
2) how many level of links are best for the information seekers in case
they get frustration and give up in searching procedure?

Any usability studies related to these two questions?

Thanks in advance,
have a good night!

Sandra