Why the Epsom ground is likely to be softer than advertised

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Using the going model used for the Racing Post’s revolutionary daily form study newsletter The Edge, Harry Wilson assesses the true state of the likely ground for the Derby meeting.

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Epsom official going description: Good to soft
GoingStick reading: 5.5
Forecast: Showers

Projected going description: Good to soft, soft in places (6.1)

Epsom was hit with 25mm of rain yesterday morning, which led to the GoingStick reading on the Derby course dropping from 6.6 to 5.9 when a new figure was reported at 12.45pm and the description changing from ‘good, good to firm in places’ to ‘good to soft, good in places’.

The description that came with the original figure of 6.6 reported on Monday was more than fair when looking at historical data from the track, although our model suggested it was verging on a flipped going of ‘good to firm, good in places’, and to give the course plenty of credit, Tuesday’s updated reading of 5.9 and description of ‘good to soft, good in places’ aligned well with our model too.

The track hadn’t changed the description this morning following a further 8mm of rain, but did drop the GoingStick reading to 5.5, which is the lowest reading in our data set and led to our model predicting that the ground was softer than advertised.

An updated description of 'good to soft' came through from the track shortly after 4pm, confirming that the ground had softened, which our model had already projected.

The caveat is that Epsom’s r-squared value is just 0.39, which is like saying the description is 39 per cent predictable from the GoingStick reading, so it’s not the most accurate track out there and therefore makes our model’s prediction less conclusive.

For that reason, it is worth noting that a similar figure (5.6) and identical description to today – good to soft, good in places (was changed to soft after race three) – was reported at Epsom’s meeting last September, when times indicated that the ground was no worse than the slower side of good.

However, given the track is already reporting its lowest GoingStick reading in 18 months and there are showers forecast over the next few days, our model’s prediction of ‘good to soft, soft in places’ may not be too far off, although times of the races on Friday’s Oaks card will paint a much clearer picture.

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The Edge's going model explained

This tool takes the politics and guesswork out of going descriptions. It uses readings from the GoingStick, which provides a scale from zero to 15 to outline ground conditions at a racecourse, and maps these to reported going descriptions.

Not all tracks are the same, but over time a linear relationship should build up at each track between GoingStick readings and going descriptions. In order to create that relationship, we convert descriptions into a numerical scale from one to 16 that is meant to mirror the GoingStick.

By plotting today's GoingStick reading against this relationship, it should be possible to check whether the reported going that day matches up with the relationship that has built up at previous meetings. We are in effect measuring the clerk of the course's reading today against their previous work. Think of it as an early-warning system against rogue going descriptions, which can be the scourge of ground-conscious punters.

Here is the scale The Edge uses for different going descriptions:

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