I have studied bookmakers prices for quite some time now.
I have firmly come to the conclusion that one of the best free sources of ratings are the bookmakers opening prices.
These guys do it for a living, their entire liability and income depends on ratings.
Rob Waterhouse once wrote to me, that if he priced the favourite wrongly, he'd be out of business very quickly with the amount of money he deals with in each race.
Price movements come from punters opinion, but also from whispers.
Often the whispers are right, actually at an astonishing rate.
However, if you got on at top fluctuation on only the whispers, you'd make a killing.
But all too often the bird has flown and punters sacrifice profit for strike rate.

So, taking two independant sets of stats, we can see definite trends, that might just help backers and layers on Betfair.

Looking at the UK races for the last two days:

I looked at all horses that opened favourite or joint favourite.

83 of them.

Of those 83, 50 drifted resulting in a loss on turnover of 3.91% At Betfair SP

As the bookies, notoriously open "a little shorter" resulting in higher overrounds at the start of betting, one would expect most to drift, especially as support comes for other horses.
A lot of these did not end up favourite.

31 of the 83 firmed for a LOT of 65.16%

These figures are just for demonstration, they are actually not indicative of the longterm percentages, due to a lower number of favourites winning over the last two days.
However, the trend remains the same - just smaller and greater.

So we add the bookies overround to the opening price, and we have the exact price the bookie thinks is breakeven.

Anything above that is profit, anything below is loss (for backers)
Anything above is loss, anything below is profit (for layers)

However, I got rattled three days ago,when the entire day was full of firmers winning at an astonishing rate.

And yet the next two days, I would have made up all the losses...and made a handsome profit to boot.

It's very easy to get rattled and lose focus, when almost 30 races go against you race after race after race.
The same happened to me, two years ago, when it went on for days on end.

The difference being that one can remain composed (reasonably) when one strikes a run of outs backing, you're only losing your stake, but a run of lays winning can decimate the bank very quickly, it almost compounds into significant damage.

The old rules of percentage of bank backing can not be applied to laying, they must be trimmed to miniscule percentages to protect the bank.

In other words, back 10 losing even money favourites and you've lost 10 units
Lay 10 winning even money favourites on the trot and you've also 10 units

But when you get over the even money price, the damage compounds - laying.

So from my experiences, I just thought I'd share some observations that might help backers and layers.

Do the reverse of the crowd, and profit - but when laying rethink the entire percentage of bank situation or you might cop a severe and savage beating like I did

I hope this helps someone else.

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