G'day LuckyBoy,

I would like to offer my advice/opinion as I believe that prizemoney factor can be very misleading, as outlined by other learned contributors. It is quite common for owners of ordinary horses to accept for races in which their horse has no realistic chance. They hope to run in the first five to receive very attractive prizemoney(although their horse may be beaten by up to 20 lengths). This distorts the real class of their horse and a form student must take this into account when assessing the all factors.
To assist you in refining the chances in any race I suggest looking at the following factors:
1) only consider any horse finishing within two lengths of the winner last start(no matter where it finished);
2) look for a horse down in class and field strength from that run;
3) look for a replacement jockey, especially if a well-credentialled jockey replaces an apprentice.
I am confident that these factors(filters)will prove more beneficial than the prizemoney factor).

I hope this may be of some assistance.

Cheers.