Questions about spamicity

[Michael Rensing]

Does it make sense for a message to have spamicity=0.000000? That's
what's getting put into my message headers. As in:

X-Bogosity:  No, tests=bogofilter, spamicity=0.000000, version=0.13.2.1

It seems to me that for a statistical method, there should virtually
never be a perfect 0 or 1 for a rating. However, that's what I'm getting
for all of my messages.

When I run bogofilter -M -v against my spam mailbox, only a few have a
non-zero spamicity. Any ideas what's going on? Do I need to reset the
database somehow? If so, how?

TIA
-- 
Michael Rensing <michael.rensing at shaw.ca>