If you analysed every race with a mathematical equation you'd end up with patches in your jeans.
But here's one that just might work. It might help sort out the A$1 million Australian Oaks at Randwick on Saturday afternoon.
Australians are using last week's Australian Derby and the previous week's Vinery Stakes as a way to find this Oaks winner.
By far the best form reference is our own Derby at Ellerslie.
Tavago had an interrupted preparation for that and after an indifferent passage flew home into sixth to record the fastest last 600m and 400m all day.
He went to Sydney and destroyed the opposition in last week's Derby.
Second behind him was today's Oaks favourite Jameka.
Valley Girl was hampered early in a six-horse shuffle with a round to travel at Ellerslie and finished strongly into fourth. She may even have won with a better run from her wide barrier.
The maths comes in when you consider there is probably very little distance between Tavago and Valley Girl or, for that matter, the other New Zealand pair of Sofia Rosa and Capella.
Jameka couldn't get closer than 3.3 lengths to Tavago last week and you can be reasonably confident Valley Girl would have.
Jameka has the added disadvantage of having only a seven-day backup from that very hard race.
Valley Girl is much better off with an extra week after her excellent second in the Vinery Stakes.
Adding that up, you have to take a shine to Valley Girl's chances.
Track conditions will be important. Randwick will probably start just into the slow zone early this morning, but if showers stay away - and that's probable - there is every chance of an upgrade. Valley Girl does not mind a little cut in the ground. Co-trainer Chris Gibbs, now back in New Zealand, was at Randwick last Saturday morning when Valley Girl went through a serious piece of work.
"All the Australians were complaining how wet the track was. Alex Forbes rode Valley Girl and he came in and said she just relished the footing."
Sofia Rosa will probably handle an affected track better than Capella, who appreciates good footing. Both are extremely talented and tough at the end of their races, something of great value at Randwick.
An extremely interesting race.
Weight is a critical factor over 3200m because of the much longer time horses have to race at full speed under it compared to sprinters.
Therefore the 57.5kg topweight former New Zealand-trained Who Shot Thebarman has to carry in Saturday's A$2 million Sydney Cup levels the race out a little with his stablemate and joint favourite Libran.
For all that it's difficult to forget Who Shot Thebarman stretched Preferment's neck in the BMW last start. That's enormous form for this race.
Libran has come through slightly easier handicap races, but he has won his last three straight and has just 53kg.
The pair's staying power stands them out in this race and when was the last time your saw a Chris Waller horse weaken on the line.