Ubetido

Allow me the liberty of re-phrasing your question to read, "What is the INCORRECT trifecta structure."

I'm not going to masquerade as some sort of latter day trifecta expert and so rely on statistics contained in 'Gambling into the Ninties - A better guide to odds', Hans EISLER 1990 Kangaroo Press. I know not of Mr Eisler's fate except to say as a mathametician and keen student of the punt he pioneered the application of computers in unravelling the mysteries of the turf.

Our friend crunched the results of 5,346 metropolitan races and compiled what he termed, "The Form Guide to ODDS".

The ODDS form guide revealed the success rate of Starting Prices calibrated from 1/3 through 100/1. For example, horses with SP 5/4 won 39.9% of races - thus if you could secure 6/4 a punter would break even in the long run. At SP 5/2 - needed 13/4 to break even. At 6/1 - 8/1 and so on and so on. The longer the SP odds, the harder it became to secure the break even odds at some stage during the betting.

He examined 306 races where the favourite SP was 5/4 or less. Using the favourite (F) as a roving banker with the field(X) he recorded the following trifecta results:

F,X,X $32,564 bet $25,856 return 20.6% LoT
X,F,X $32,564 bet $23,804 return 26.9% LoT
X,X,F $32,564 bet $23,902 return 26.6% LoT

Betting F on a straight out win only basis showed a 9.8% LoT.

Conclusion: What one should NOT DO in structuring a trifecta bet is transparent.

A successful alternative remains less obvious - at least to my eye.