Autoanalyze settings with zero scale factor

Some of my very large tables (10 million rows) need to be analyzed by
autovacuum on a frequent basis. Rather than specifying this as a
percentage of table size + base threshold, I wanted to specify it as an
explicit number of rows.

I changed the table-specific settings so that the ANALYZE base threshold
was 5000 and the ANALYZE scale factor is 0. According to the documented
formula: analyze threshold = analyze base threshold + analyze scale
factor * number of tuples, I assumed that this would cause the table to
be analyzed everytime 5000 tuples were inserted/updated/deleted.

However, the tables have been updated with tens of thousands of inserts
and the table has still not been analyzed (according to
pg_stat_user_tables). Does a scale factor of 0 cause the table to never
be analyzed? What am I doing wrong?

I'm using PG 8.2.1.

Thanks,
Jeremy Haile