Another Lay system

[El Stevo]

New poster to this site although been a regular reader for some time.
I appologise if this has been done before (seen similar things) but I think it's a little different.
Anyway, I tested a system last week and the results were:-
82 layed bets (all 10 unit stakes) 64 (79%) winning bets and a profit of 120 units.
I am thinking of doing a paper trial but would would appreciated the experts view/ideas/input so that I can refine it before starting.

Basically, what I will do is take the odds of one bookmaker (I have used Paddy Power) and if I can lay on betfair at odds of no more than 10% different to these odds I will do so. My thinking is that I will basically be acting as a bookmaker (and as they say, you never see a poor one). The odds that I lay at are obviously higher than a bookmaker but if I can limit the difference to no more than 10% I should get similar results to the bookmaker. They must have a margin of at last 10% built in to their odds and I will not have any of their overheads.

A few things that I have would appreciate advise on:-
1. Does anybody know what a bookmaker generally has as a profit margin. I've assumed it to be at least 10% but if if I'm wrong maybe I need to change this criteria.
2. I've used Paddy Power because I think they generally offer reasonable odds but must still have that profit margin. Is that a fair assumption (I don't normally bet on horses - more of a football man).
3. I intend to limit the odds layed at to 7.00 simply because I don't want to get hit for a big one. However, the principle must be the same on long odds (although maybe the margin is different?) and therfore maybe I should not be using this restriction.

Any advice very welcome and then I'll get it up and running.

Cheers

[aliando]

to PL mate - good luck!

[davyboy]

hi & welcome, im fairly new to pl & enjoying ever minute of it!!, so just to clarify you are backing them high & laying them low then?, using pp as your everyday bookie, interesting theory, you play bookie, could you elaborate a little & perhaps write out a few examples if thats ok?

[El Stevo]

Daveyboy

No I'm not backing them at all, just laying. So for an example, take the 2 .40 at Newbury yesterday.
Paddy Power were offering 6.00 on Snowy Morning and 7.00 on Alragante.
I could lay on betfair at 6.4 and 7.6 respectively, both within my 10% margin. Neither horse won so 20 unit profit.
In the same race Denman was 6 with PP and could have been layed at 7.2 but that is too wide a margin.
Hope this clears any confusion.

[davyboy]

got ya!, got that all wrong although what i said may be an interesting theory??, any takers??.

how long have you been paper testing?