This could be shot down as backfitting (but it's not), but I actually came up with this by mistake, an error in number of runs from a spell ..... but the theme of this thread is evident.


Rules
1st run back from a spell - anywhere
2nd run back from a spell - Fin between 2 and 9 over less than 1201m
3rd back from a spell - Fin between 2 and 9 over less than 1401m
4th run back from a spell - Fin anywhere over a distance of > 1400m
SP between $4 and $30
Career starts 8 to 21 (tks sarge)
Career wins >2
Metro horse

BTW Fin between 2 and 9 is one of my standard filters, so this is NOT backfitted. Career starts is one of sarge's good filters and again it's NOT backfitted. SP $4 to $30 as above, NOT backfitted. Metro horse weeds out the rubbish and is standard, NOT backfitted. Career wins >2 is standard, NOT backfitted ..... and they're not 5 of my 6 specials Vortech, some are tho'.

So we've got a horse that's had 4 runs this time in, increasing in distance, and we don't care where it finished first up, or at it's last start. There's no way I'm going to reveal the POT, but suffice to say it's good. AND it's consistent with what I posted in my system where I had a POT at all runs, then in a couple of darky's systems where the POT was OK / Decent when backing / following a horse a few runs in.

So, there's more than one way to skin a cat, but the concept of following a horse that's shown something, has improvement left in it, seems to have merit.

Runs since spell = 4
SP between $4 and $30
Career starts 8 to 21 (tks sarge)
Career wins >2
Metro horse

1st run back from a spell - <1201m
2nd run back crom a spell - < 1401m
3rd run back from a spell - > 1599m

So, there's no "form" (ie; finished 2nd, or 3rd beaten 2 lengths etc carried 54kgs, blah, blah, blah) - ONLY an increase in distance

4th run back from a spell ..... we don't care !!!!!!!!!! lol !!!! We just don't give a fat rats clacker !!!!!

And it shows a POT of 11% on a S/R of 15% ..... You mightn't like it, but there's no form involved. I DO like it, it's similar to my best system ..... and you can test this dudes !!!!!, and the place results are even better YOLO !!!!!!!

Sincere apologies to the Form Students and Ratings Disciples ..... NOT !!

Bwahahahahahahaha !!!!!!!!!!!!!!!!

Sorry but I have to disagree with here Barny, all bar the Metro filter is backfitted regardless of whether you say they are one of your standard filters or not.

Before you jump up and down and get defensive probably 90% of all system filters are backfitted in some way and if it works for you then great but don't kid yourself by saying that those filters aren't "backfitted".

Mattio - Can backfitting work long-term?

Hi Barny,
All these little "Systemettes" are fun but I,ll still stick to form and ratings.

But in saying that and it is approaching Xmas after all I,ll add the "World Famous " to" Partys Plum Movers" on "Good TC and hope for a excellent result.

Ho Ho Ho

Good question Vortech - it depends on the type of filters and the extent of the backfitting. Backfitting in some form or another is present in ALL systems otherwise how else does a system get developed? You back test certain filters, analyse the results and make adjustments then you back test again - this is how a system is developed. I prefer to tailor the results to suit the filters as opposed to tailoring the filters to suit the results.

What I mean by that is working with filters that I know are quality filters (based on backtesting - there's that word again) and then making adjustments around that. What alot of people do which I believe is the wrong way to go is that they manupulate filters to suit their results and end up with filters of this nature:

- days last start 9-37 (no logic here but it suits the results)
- last start finish 2-9 (not knocking Barny specifically here but why look at a horse that finished 9th last start especially when you have no idea of the margins)
- win percentage 23-82 (again no logic here but it suits the results)

These are just a few examples but there are many more. If I were using these types of filters (and I do) I would go about it in this way:

- days last start 7-21 (or something of this nature, you know the horse is likely to have a good level of residual fitness and the days are a logical number)
- last start finish 1-3 or 4+ (this depends on the type of system I am doing, one that looks for consistent horses would be 1-3 and one to find value horses would be 4+ but I would generally use this in conjunction with a margins filter)
- win percentage 30-100 (this is far more logical and not tailored around results)

Again these are just a few examples but I believe it all comes down to the individual being honest with themselves about why they are including a certain filter. If there is no logic about a filter that adds value then I suggest it will fail longterm but if the filter has logic (real logic, not punter's logic) then I suggest it has a chance of working longterm.

Here is a system that I use, I have added a couple of extra filters but here are the base filters:

7 days to last start
No change in distance
No change in weight
No change in prizemoney
Same track as last start

Basically this system is looking at horses racing under similar conditions to last start backing up after 7 days. It is a simple system with simple and logical filters that finds some great value winners with an acceptable strike rate and average price winner around $10.

Just my thoughts on another issue to is the definition of "longterm". I don't test back any further than 2010 due to the changing nature of the industry and the distasterous effect of EI in 2007 which I believe still had consequences up until 2009 and even early in 2010. I have found that many systems have a drastic change in results when testing beyond 2010.

Basically what mattio is saying is if say one of your filters is a horse must have a winning % above 23.37% then you've clearly backfitted to get the 'best' result. However if your filter is it has to be above 20% or 25% then thats not so bad as your using general numbers and not backfitting to a precise number.

pretty much the way I approach thing mattio, good post, if one cannot logically explain why a filter 'appears' to work, it's probably backfitting.

__________________
"Now let me get this straight - Whatever I do don't bet this horse?"

EDIT: Which is why a lot of the systems posted on here aren't really worth 2 pinches of salt to be bluntly honest. A lot of them have been clearly backfitted when you have 10 filters that produce 70 selections since 2009 with a POT of 50%, blatant backfitting if you ask me.

Would much prefer something that has 5 filters with 1000 selections since 2009 and a POT of 30%. Obviously there are other things at play like strike rate that may adjust whether your comfortable with a system or not, but you get the drift.

Note: Not having a dig at Barny's system in this thread though, I think it has real merit, i'm just talking in general.