• Part 2 of our guide to framing a market
• How to quickly and easily deal with the impact of scratchings

Yesterday we took a look at the basics of how to build your own rated markets. There’s quite a bit to it but once you have your head around the maths of it, it’ll all be very simple.

Once you’re done however, how do you deal with a spanner in the works?

When it comes to rating a race, that spanner comes in the form of scratchings. When a horse is taken out, it shifts the entire complexion of the race.

#### The effect of scratchings

The key basic to remember is that a scratching improves the hopes of every other horse – they now have one less opponent to beat.

In theory, all you have to do is remove the scratched horse from your numbers and restate the chances of every other runner.

#### Scratchings: the market

Let’s look at yesterday’s example of our final rated market:

For a simple example of a scratching, let’s say Horse B is taken out of the race.

After the market is adjusted it looks like this:

The market is still constructed the same way, it’s simply done so without the scratched horse. The probability factor for each horse is the same – but the total is obviously lower, so the market percentages move in line.

That’s how the scratched horse’s percentage is re-distributed across the remaining field.

#### Scratchings: what information do you need?

It’s fine to do all of this if you’ve set the market yourself, but what if you’re following somebody else’s prices? Can you still reset the market for a late scratching?

Yes – all you need is the rated prices.

Rated prices can quite easily be converted to the market percentage, from which you can reset after a scratching.

Again, let’s check at an example…

It’s just a case of taking the market percentage of the remaining runners, and restating them to 100% by redistributing the scratched horse’s percentage to each horse in line with their chances. Simple, right?

If it doesn’t feel simple now, it will once you have your head around it.

Having a model which can quickly readjust things for you in the event of a scratching is very, very useful: especially when they happen behind the barriers and you only have minutes, or even seconds, to recalibrate your bets. A great example of this is the ratings sheet you get for every Melbourne Metro meeting with Trevor Lawson’s Melbourne Ratings service. The Excel-based ratings sheet has a simple function where you just tag a horse as “Scratched”, and the race restates everything – new rated prices and recommended stakes – with the click of that button.

Punt like a pro with Trevor Lawson’s Melbourne Ratings.

As well as a full set of rated prices, speed maps and suggested bets, you can spend each and every raceday with a pro punter: the Melbourne Ratings Live Page gives you direct access to Trev himself to ask whatever you like.

If you're keen to win, it’s the only way to punt.

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