I'm trying to avoid favourites too, Duck, I've been trying to do so successfully for years, trying being the operative word. I just came up with that impromptu "system" while mucking around with the figures.
Thanks for the reference, happy for you to take a look at the data.
Mr Logic, the 1.8 lengths was derived by pure curve fitting; from memory, those winning between 1.5 and 1.7 lengths broke about even and thereon showed a loss.