% of pool that significantly changes dividends
 

Hi all,

My question may be easy to answer or it may be quite difficult - My brain is already in holiday mode, so I'm not sure I'm thinking about this correctly. I understand that realistically any bet that I place has an impact on the dividend of that horse. What I'm after is the point at which my single bet significantly changes the odds.

For example, say I have a 70% place strike rate and those nags have an average place divvy of $1.60. My PoT would be 12%. However, if my bets are large enough that I reduce the average place divvy to $1.40, i'm now making a 2% loss on turnover.

At what point might my bet of $X into a place pool of $Y cause this to happen? I guess it's related to field size and the spread of other place bets over that field, but I'm not looking for a thorough mathematical answer; just something like "if the place pool is $10,000 then a $250 bet will do this."

It depends entirely on the pool size and distribution of money on each horse.
In a $10,000 pool, a $250 bet on the favourite won't bring it from $1.60 to $1.40, it will nudge it towards $1.55.
However, that same bet on an outsider can make a very large impact in such a small pool.
If the favourite is odds on, your $250 bet shouldn't make it budge at all, but you have to worry that other people might follow your bet.

Best advice is to take best tote or tote plus product with the bookies if applicable, you can even take this on betfair using the fair price product.

Thank you for the swift reply, Chrome. That was exactly what I was looking for.

Great question, though your not looking for a thorough mathematical answer but what needs to be understood is Place Pools are split into 3 pools, you should convert your tote odds to Natural odds then to $'s on each runner (as this will in the end determine the your size of wager which is the balance of risk and reward), this will then give you the "Tote Take out %" you then need to understand how this take out is applied to each runner (clue! it's not even across the board).
Then to calculate the investment to each runner.
Excel provides an add-in called solver that can provide your bet size within seconds set to the parameters that you have previously determined as your winning %'s envelope.
If you do venture down the solver path, your "target cell" will be the sum of your total "probability times Log" or probxlog for all runners not just your rated or favoured runner.

Sorry Kaiser, I missed that this was place betting.
Therefore your $250 bet could well drive the odds from $1.60 to $1.40.
I'd be placing your money on Betfair place markets if you can.

The Betfair Place markets can offer excellent valuse compared to the totes.

Especially if the selection is not the fav.

I have seen many a time where say a horse pays 1.60 on the TAB
And 2.60 on Betfair
That's .60/1 compared to 1.60/1
That's a massive difference of 167%

One can make good money place betting with percentages like that.

Note:
One has to convert decimal odds to fractional odds to work out the percentages correctly.