bogotrain

[Bob Vincent]

Weird.
I finally accumulated enough ham to run bogotrain, and here's what it
came up with:

---cut---
db_cachesize=2
robx=0.539781
min_dev=0.178
robs=0.0178
sp_esf=0.011573
ns_esf=0.004228
spam_cutoff=0.320443    # for 0.05% fp (1); expect 0.03% fn (1).
#spam_cutoff=0.282543   # for 0.10% fp (2); expect 0.00% fn (0).
#spam_cutoff=0.270560   # for 0.20% fp (4); expect 0.00% fn (0).
ham_cutoff=0.340
---cut---

I don't understand why the suggested spam_cutoff is lower than the
suggested ham_cutoff.  Can anyone explain?