Here's a quick and dirty, yet surprisingly accurate way of coming up with some pretty good selections. Betting them wisely creates a profit.

The System

Note the class of the current race.
For each horse note down it's average price in that class of race for past starts.
The average price is converted to a percentage, which becomes a rating out of 100.
Horses with no starts at the class, become a rating out of 100 given the field size (a default value).
Then price up the field to 100% book.
Back the overs and lay the unders.

Examples

The Robert Sangster Stakes at Morphettville 29/3/2008

Horse
Miss Andretti   (rating 18.25)
St Trinians   (default rating 7.69)
Lucky Diva   (rating 3.64)
Miss Fantabulous   (rating 3.30)
Juste Momente   (rating 9.26)   Winner
Zipanese   (rating 2.61)
Dollops   (default rating 7.69)
Emilydelago   (default rating 7.69)
Bel Mer   (rating 4.81)
Serious Speed   (rating 9.40)
Sleek Chassis   (rating 9.90)
Gibraltar Campion   (default rating 7.69)
Spectacula   (default rating 7.69)

Pricing
Miss Andretti   $5.48 vs tote $1.40
St Trinians   $13.00 vs tote $18.80
Lucky Diva   $27.47 vs tote $38.40
Miss Fantabulous   $30.30 vs tote $41.50
Juste Momente   $10.80 vs tote $31.60   Winner
Zipanese   $38.31 vs tote $32.70
Dollops   $13.00 vs tote $36.60
Emilydelago   $13.00 vs tote $125.40
Bel Mer   $20.79 vs tote $6.30
Serious Speed   $10.64 vs tote $13.70
Sleek Chassis   $10.10 vs tote $32.30
Gibraltar Campion   $13.00 vs tote $66.60
Spectacula   $13.00 vs tote $144.60

Forgetting the horses whose price was devised from the default rating we have:

Overs
Lucky Diva   $27.47 vs tote $38.40 Back
Miss Fantabulous   $30.30 vs tote $41.50Back
Juste Momente   $10.80 vs tote $31.60   WinnerBack
Serious Speed   $10.64 vs tote $13.70Back
Sleek Chassis   $10.10 vs tote $32.30Back

Unders
Miss Andretti   $5.48 vs tote $1.40Lay
Zipanese   $38.31 vs tote $32.70Lay
Bel Mer   $20.79 vs tote $6.30Lay

__________________
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