The Arc: Should you believe what you read and hear?

Danedream winning the 2011 Arc.

Europe's richest race takes place at Longchamp on Sunday. Simon Rowlands attempts to separate the myth from the reality...

The Prix de l'Arc de Triomphe, as we keep being reminded, is the greatest horserace in the world, and this year's contest promises to be as gripping and very nearly as high-quality as usual.

We might have lost last year's winner Danedream and Nathaniel at a late stage, but we look to have acquired the 2000 Guineas and Derby winner Camelot, to go with a Japanese Triple Crown winner in Orfevre, a Prix du Jockey Club winner in Saonois and a possible Breeders' Cup Turf one-two in St Nicholas Abbey and Sea Moon.

Received wisdoms abound concerning the Arc, as they do with most big races, so I thought it worth looking at some of them in greater detail. For this, I took all Arcs run this century - twelve of them in all - and measured performance by percentage of rivals beaten, which was then transformed into margins better or worse than average.

It is, of course, meaningless to state that "eight of the last nine Arcs have been won by three-year-olds" (which is true), without considering what sort of figure could be expected given that age-group's representation.

Furthermore, judging a horse's performance by a binomial "did it win, or did it lose?" is clearly a crude measure. Wins come in different forms and losses come in many different forms too. Percentage of rivals beaten allows for this to a large degree and crucially takes into account field size, which gets left out in simple strike-rates.

Draw
Horses drawn in stalls 1 and 2 (nearest the inner) have beaten 58% of their rivals, where 50% could be expected. This is equivalent to an advantage of about 1.6 lengths. Horses drawn in stalls 11 and higher have beaten 46% of their rivals, equivalent to a disadvantage of about 0.8 lengths.

Conclusion: there is probably something in the draw, but less than often seems to be assumed.

Age
Three-year-olds have provided the majority of Arc winners (75% this century, 63% in the race's near-100-year history), but they have also been the most represented age-group in recent times. More to the point, their percentage of rivals beaten this century is at 52.7%, or only just above par. This is equivalent to about 0.5 lengths advantage. There is little between four-year-olds and horses older than four.

Conclusion: there may be something in the idea that three-year-olds are favoured in the Arc, but any advantage is small, and much smaller than might be imagined at a cursory glance. It seems more relevant that the classic generation seems weaker this year than usual.

Sex
Females have provided just 34 of the 180 runners this century but this group has overperformed in terms of percentage of rivals beaten. 60.1% is equivalent to an advantage over expectation of about 2.0 lengths and of 2.5 lengths over the remaining male runners.

Conclusion: whether it is that fillies and mares thrive at this time of year, or that there is some sort of selection bias in that only the very top horses of that sex are aimed at a race like the Arc, it is difficult to escape the fact that they have a good record in the race, and that seems to apply going further back too.

There is a further received wisdom worth investigating where the Arc is concerned, and that is one I slipped in at the beginning of this piece.

Is the Arc truly "the greatest horserace in the world"? Well, it depends on your criteria. But, in terms of race strength derived from the average Timeform ratings of the first three in the last five years (weighted as 1/N, where N is the finishing position), the Arc comes out on top. But only just!

Its figure is 127.9, whereas the Queen Elizabeth II Stakes (bolstered by Frankel's participation in 2011) is 127.8, the Breeders' Cup Classic (which had a substandard year in 2011, else it would be top) is 127.3, the King George VI and Queen Elizabeth Stakes is 127.1 and the Irish Champion Stakes is 126.8. The Champion Stakes at Ascot is likely to build on its 125.9 and managed 131.3 in 2011.

Some way back are the Dubai World Cup (124.2), the Japan Cup (123.8) and the Melbourne Cup (which is a handicap, on 120.6).

The "conclusion"? That the Arc is indeed the most consistently high-quality race on the planet, but that it cannot afford a substandard year if it is to hold on to that title.

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