Sun 28/04/2024 Seletions.
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@brendan-gillen we do pre-match xg on the software, if you go through the getting started pathway that will teach you how to use the software: https://forum.betfairtradingcommunity.com/category/10/new-members-start-here

You can get the live xG in play on bookie sites like Bet365 for free

I do an almost identical strategy and selection process on WTA so thought I’d create my own filter using @Ryan advice here. Works well, thank you!

Player Matches Won >= 0
Category WTA-Singles
Scope Last 10 Matches
✅ Restrict To Same Surface Type

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In the second and third images image you can see I’ve gone through the list of qualifying selections and identified the favourites by checking the match odds first, then checking if they have an equal or lower amount of wins to the underdog and selected them to download. I do this by percentage so for the highlighted the match, for each players last 10 matches on the same surface type, the favourite has a 40% win rate and the underdog a 70% win rate. Nice.

You can then dive as deep as you like in to further match analysis. In the forth image you can see that on Breaks of Serve in the past 10 matches, the underdog has broken serve first 50% of the time and the favourite 40%.
For this strategy I am probably going to discard any matches where the underdog compares badly to the favourite on this statistic.

@Paul-Hill don't think we could even investigate that, as there is no strategy to work from. perhaps something in the betting rules was slightly different, impossible to know if it wasn't saved unfortunately.

if you are 100% sure create it again and see if the results align with the saved one, save both and let us know the names if there is an issue and we could investigate.

@Paul-Hill The outsider is the horse with the highest price.

2nd outsider is the horse with the 2nd highest price, etc. Basically the opposite of the favourites.

The outsider setting works in conjunction with the other betting rules, so for example if you set your entry time as 10 mins before the race, it's basically going to give you whichever horse had the highest price at 10 mins before the race.

@Patrick-Murphy Having looked at some of these, it looks like they're due to gaps in the prices. So basically short amounts of time where we weren't able to capture price snapshots, so your exits have either been missed completely or recorded later than they should have been.

These gaps can be due to latency or brief outages of the Betfair API and occasionally due to some issue our end, like the server issue I posted about recently here.

We regularly plug these gaps where we can using the Betfair historical data, and we've recently improved our audit scripts to better identify when they happen, so have been going through the whole database again to apply this improved method. It's a fairly big task but should be finished by the end of next week.

Sometimes when the issue is at Betfair's end, the data doesn't even appear in their historical data, which means we won't be able to plug the gaps at all. This will represent a fraction of a percent of trades, but I can understand that if you're backing at very high odds and large stakes, it could skew the profit figure.

Maybe we need a way of marking these in the database. We could also add some kind of "report and exclude" button to each individual trade in the results table, so that if you spot any of these yourselves, you can submit them for review and make them not appear in your backtesting results.

I'll finish the DB audit and then see what we can do to deal with any issues that still remain.

@Simon-Hardy interesting, not tried this but keep me updated with how you get on!

@Martin Hi, thanks yes i think I’ll have to do this as you say to find out. I track the trades so in time should be able to.

I think getting out of a losing trade with the smallest loss could be something i focus more on rather than staying in for slightly greater wins. Kind of the same thing but the opposite.

@Adam thanks very helpful

Thanks, Adam, that's really useful to know 👍 it has been bugging me.

@Barry-Dewar Why do you think that is?

Nice done @james-everard

@declan-henderson I used to be, spent 14 years doing it. Happy to help on that sport was my fave sport to trade.

@Martin it feels really good to be honest Martin. Feels like I've graduated trading primary school and am now off into secondary school for a time being. Shout outs to you and @Ryan for the content and advise aiding the journey.

Big things are on the way - I can feel it!

@Kurtis-Steven-Graham Hard to say.

It's the actual rules that tell you what is happening.

@Martin I'm really looking for a standard approach to calculating my stakes as a percentage of bank across various strategies (rather than based on a specific strategy). Generally I'm backing but some lay strats.
So for example, one strategy might have a 4% strike rate, odds range 20-100, average odds 38, longest losing run 133 and an ROI of 24%. I know I'll need to ride out long losing periods and my gut feel is I'd want at least a 200 point bank, probably more. If I plug the above into a basic Kelly calculator it gives me 1.41% as the 'Fraction of bankroll to wager' which equals a 70 point bank. That's way too low in my view.
2nd scenario - 24% strike rate, average odds 8, longest losing run 22 and an ROI of 37%. The basic Kelly calculator gives 13.14% as my stake %age (!) but my feel is this would work with a 100 point bank.
I've seen Kelly calculators with options to add multiples for a more cautious bank size (BFBM has a 'Divisor') and maybe I just need to use that but adjust the Divisor based on the average odds?
I've always used a level stakes approach and that's probably why I'm struggling with the percentage of bank that Kelly calculates. I also need to adjust to the percent of bank betting approach rather level stakes
Anyway, any thoughts from others with more experience using a percentage approach will be very welcome
Cheers