Assuming you cannot know with certainty the price movements, and you allocate amounts for back and lay at various prices, how can you engineer a risk-free situation, other than luck or hope that the necessary bets will be matched?

shoto,

Yes you can actually be sure that some prices will move out and others will come in, especially when bookies are winding prices in, but it hasn't hit Betfair yet.

Also, just with a little experience, I can spot a price that I know with a good deal of certainty will come in or blow out, especially on outsiders. I sometimes get it wrong, but the times I get it right more than compensates.
If a price doesn't move like predicted, I can always lay off on another runner.

I can have five runners running risk free, and then have a free bet on others and still come out ahead.

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Thanks CP. Are you mostly looking to get set-up with lays, or do you go in with a mix of back/lay from the beginning?

Shoto,

To be honest I don't have a set strategy for every race, although the principle is the same. I read the market and make decisions on the best approach and may have three different strategies in the one race.
I approach a race with an odds on favourite quite differently to an open 4/1 the field race.

As an example: In a trot race tonight I assessed (better word than "knew") that the long odds on favourite would firm in the market and the longer horses would blow in the market, so simply backed the odds on pop and layed all the longies at shorter prices than they'd end up on the tote. As they were scoring up, I was able to lay the odds on horse @$1.15 and had backed it @$1.51. I also bet back on the longshots on the tote which were "free" bets.

If the shorty won I would have made a small profit
If the shorty lost I would have been square if a longshot didn't salute.
If a longshot saluted I would have made a huge profit @ no risk.

The best scenario was a very nice profit
The worst breaking even!

As it stood I won a small amount for the race as the odds on favourite held off challengers...one of those challengers was one of the longshots .

But multiply betting like this over 100 races and you have to end up in front as long as the prices are right, although of course it doesn't always go exactly to plan and this is only one strategy in the armoury.

Someone once told me I'd go broke laying every favourite on Betfair (Racing, Pacing, Australia, U.K, South Africa, United Arab Emirates etc).
But I'm doing it, and winning better percentages than I thought.
The only thing I avoid is the USA.

__________________
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Thanks CP, very interesting stuff! For some (ie me) it would not be an easy thing to do. I can understand what you have said recently that it has not happened without alot of study and work.

Your comment about determining a true price is intriguing, and surely must be a huge key. (Not that I'm asking you to say anything about it.) That you have created a methodology that is reliable and low-risk is excellent. Good success to you!

One outfit developing an automated betting product, has published full results of a theoretical overlay betting splurge on the 1st Power Pay weekend.

It reported a staggering 24.29% POT from 197 bets and 22 wins.

Unfortunately there are some non-key errors in the figures, and the experiment has not been updated for the subsequent days.

I am in no position to vouch for the validity of those figures and whether they could be sustained through the 700 or so bets for the full Power Pays.

But, in rough calculations, if you bet 2% of your bank (as Kelly suggests) then you would expect to grow your bank by 0.5% every bet.

And after 700 bets the expected bank would be 32 times the original!

I'd probably be satisfied with a mere 16-fold increase.

Shoto,

I don't want to hijack jfc's thread, so I'll answer your question and post in another thread if I need to reply to you.

Whilst there are massive variations within, it is very easy to determine the overall true prices of horses. Take whatever price guide you use and simply work out the market percentage, add that percentage to the price given of your horse, the true price will be very close to what you work out, or close enough for you to make a profit laying at less than that price.
*NB I don't use published guides etc, I only use bookies prices.

Here's some justification for my research, if you were able to back every favourite on the IAS opening fixed price, you would make around 2% POT +/-.

It is also not that hard to lay at better than the final and true prices on Betfair if you weight your bets so that you have the most money on the shortest price available.

I layed a hurdler in a 4 horse field in the U.K. last night for as low as $1.31, the last lay price before they jumped was $1.80, this makes a huge difference in the scheme of things, I had assessment that this was more than 50% less than it's true price.

It lost

The night before, a horse in a 3 mile race in a three horse field was layed at $1.12, it also lost.

__________________
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Now with over 400,000 Metropolitan, Provincial and Country races!
http://www.propun.com.au/horse_raci...ng_systems.html
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One amazing achievement from Power Pays was converting a 5.95% commission to a market of 109.80%. According to the BAT for the Miss Andretti race.

There are a number of news items about Power Pay extensions. Further Victorian weekends.

But now they are trying El Gordo Quaddies! Zero % commission!

http://www.thoroughbrednews.co.nz/s...acing/?id=28160

Skinny details about the Fat Quaddie to date, but finally some news.

An obvious way of exploiting this is to skirt ~around the pair's public charity picks in the Quaddie itself, and covering those presumably overbacked perms elsewhere.

The Rosehill Fat Quaddie has been moved forward 1 race! And the Daily Double races also seem to have changed.

http://www.racingandsports.com.au/r....asp?NID=101766

This non-traditional arrangement should be tremendous for adding even more confusion to the typically malfunctioning Tabcorp experience.

Presumably many will miss getting their bets on. Not to mention those putting their Race N selections on Race N-1 instead.