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Old 08-20-2007, 02:38 PM   #16
46zilzal
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My experience with Impact factors, or databases in general, is that they dilute the specific to the general. While a general trend is fine to learn the game, once you get to that plateau you have to have the specific to differentiate you from the crowd.

I tend to follow tracks that fall outside of these generalities just for the fact that, in studying the general, the specifics are lost. It has worked well for years as race track "foot prints" are not only specific, but they respond to their own unique variations.
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Old 08-20-2007, 03:47 PM   #17
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NICE post JP and much food for thought!

I'm gonna enjoy chewing on this bit of Filet!
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Old 08-20-2007, 03:58 PM   #18
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Quote:
Originally Posted by 46zilzal
My experience with Impact factors, or databases in general, is that they dilute the specific to the general. While a general trend is fine to learn the game, once you get to that plateau you have to have the specific to differentiate you from the crowd.

I tend to follow tracks that fall outside of these generalities just for the fact that, in studying the general, the specifics are lost. It has worked well for years as race track "foot prints" are not only specific, but they respond to their own unique variations.
That just means your factors, or your database approach is too general. There is nothing inherently more or less general about using a database, it is just faster. There is no reason you can't program a database approach to be as specific as you like...
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Old 08-20-2007, 04:50 PM   #19
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I always look for subsets - say you have a general stat about last out winners. Within, that is likely a subset of those who are profitable and another that is not. (There are).
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Old 08-20-2007, 06:12 PM   #20
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Jeff P,

That sounds most encouraging and makes a lot of sense.
Thanks for posting.
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Old 08-20-2007, 06:48 PM   #21
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Quote:
Originally Posted by Jeff P
If you fail to use hidden positives in your mix then you are just spinning your wheels and doing the same thing everybody else is doing. The result will be that you will face a very tough uphill climb in trying to gain a true edge over your competition.
Jeff, I agree with your assessment of the value of hidden positives, but how long does any such factor stay hidden before it starts getting noticed and overbet, requiring you to reinvent the wheel? It seems to me that using more fundamental factors provides greater durability over time, while still providing ample opportunities for finding value (especially employing a weighted blend of several such factors, and looking at the winning chances of all horses in a field, rather than concentrating only on finding a single "angle" horse, or the one most likely winner).
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Old 08-20-2007, 08:32 PM   #22
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Warning. This post could get long. And it may ruffle some feathers because it goes against what a lot of others out there have advocated. Can't help that. The subject matter deserves a complete answer. Those of you willing to wade through it with an open mind I promise you can find some good info buried in here. What I'm posting about is stuff that is relevant to me whenever I think about the essence of winning. The process I go through isn't the only way to win. But the process I go through involves horses with hidden positives. And because the game is parimutuel in nature and because there is enough competition to make the pools pretty efficient - I believe at a core level betting horses with hidden positives is one of the requirements to being a winning player.

Quote:
Jeff, I agree with your assessment of the value of hidden positives, but how long does any such factor stay hidden before it starts getting noticed and overbet, requiring you to reinvent the wheel?
You'd be surprised. Factors stay hidden from the public for a reason. Mostly because either the factor itself is under the radar or the public refuses to believe that factor to have any real relevance. We just had a couple of lengthy threads arguing the validity of speed in workouts. In that thread I showed how to create a simple model using workout speed as the basis for profitable play. Speed in workouts isn't stand alone profitable so it was something I was willing to post about in order to illustrate how hidden positives can be used to good effect. I know of a couple of other factors (which I'm not willing to post about here) that have been stand alone flat bet profitable since I first came across them about 15 years ago.

Quote:
It seems to me that using more fundamental factors provides greater durability over time, while still providing ample opportunities for finding value (especially employing a weighted blend of several such factors...
The really interesting thing to me is that most people (and please understand I'm not picking on you) make assumptions about what I do. I get a sense from phone calls and emails a lot of people think that I use stand alone factors in a vacuum... that as soon as I discover a promising new factor that meets the criteria I posted that I'll start betting that factor as a stand alone. Nothing could be further from the truth. A lot of what I do is to take interesting and overlooked (but related) stand alone factors and use them as building blocks to create compound factors. The compound factors I'll produce will fall into one or more areas of handicapping endeavor. For example, to my way of thinking (and I need to stress that phrase so I'll say it again) to my way of thinking the five general areas of handicapping endeavor are:

1. Pace
2. Class
3. Ability from Speed Figures
4. Current Form or Condition
5. Human Connections

Every one of the compound factors that I produce is designed to represent in a unique way a horse's ability in one of the above five areas.

The interesting thing to me is that some of these compound factors outperform (in terms of win rate and roi) the sum of their parts. Then I'll turn around and use these compound factors and weight them in such a way as to create a decent power rating. So in essence the bulk of what I do is to do my own research and use what I discover to create my own compound factors and roll them together to make a power rating that is fundamentally better (IMHO) than whatever the vast majority of those I am betting against happens to be doing.

In essence I agree with you. I really do employ a weighted blend of several fundamental factors.

Continuing on with what you wrote:
Quote:
...and looking at the winning chances of all horses in a field, rather than concentrating only on finding a single "angle" horse, or the one most likely winner).
From there I'll combine the power rating with the way I perceive people will bet the race to create a reasonably accurate odds line. The more work I do (the more I re-invent the wheel) the more I find I keep making better and better odds lines.

As an aside the most accurate odds line I currently make predicts race winners with more accuracy than the public does when they select the top four horses ranked by post time favoritism. But... in practice I find that accuracy (in terms of probability) in an odds line does not necessarily translate to being able to use that odds line as a pure play or pass decision making mechanism for profitable play.

I've invested a ton of my own man hours into the never ending quest to develop better and better odds lines. No matter how accurate an odds line I make in terms of predicting race winners... and as mentioned I am able to do that with a very high degree of accuracy.... one fact remains: Whenever I simulate flat win betting EVERY horse that goes to post at odds higher than that indicated as a theoretical break even point by the odds lines I create I lose significant money.

That tells me one of two things:

1. I suck at making odds lines.
2. The pools are pretty efficient by nature.

HOWEVER, using an odds line to provide a theoretical break even point for flat betting EVERY horse above that theoretical break even point is NOT how I use the odds lines that I make.

In practice I find that when I create spot plays keyed off of combinations of hidden positive angles and run those against the odds line theoretical break even point in play or pass decision making... THAT approach consistently wins money.

And the one thing I keep coming back to whenever I think about why that approach works for me is that is has me betting almost exclusively on ONLY THOSE HORSES with enough hidden positives in their records to make this game wonderfully worthwhile.


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Old 08-20-2007, 09:01 PM   #23
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Couldn't finish editing my last post before the time limit expired... so I'll pick up where I left off...

Overlay, you posted:
Quote:
...and looking at the winning chances of all horses in a field, rather than concentrating only on finding a single "angle" horse, or the one most likely winner).
It looks like our approaches differ in the way we use odds lines.

Please understand that I am in no way saying that my way is the ONLY way. If someone else is able to do it by looking at the winning chances of all horses in a field, rather than concentrating only on finding a single "angle" horse, or the one most likely winner then even though their approach is different from what I do I'll be the first to step up and congratulate that person on a job well done.

Ultimately every player has to find an approach (whatever it might be) that works for them.


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Old 08-20-2007, 09:53 PM   #24
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Quote:
Originally Posted by Jeff P
You'd be surprised. Factors stay hidden from the public for a reason. Mostly because either the factor itself is under the radar or the public refuses to believe that factor to have any real relevance. We just had a couple of lengthy threads arguing the validity of speed in workouts. In that thread I showed how to create a simple model using workout speed as the basis for profitable play. Speed in workouts isn't stand alone profitable so it was something I was willing to post about in order to illustrate how hidden positives can be used to good effect. I know of a couple of other factors (which I'm not willing to post about here) that have been stand alone flat bet profitable since I first came across them about 15 years ago.
Even if they don't realize it, anyone making a profit is by definition betting on hidden positives. That's where overlays come from. (Just as anybody who makes a profit is therefore by definition betting on overlays, even if they don't believe in overlays.)


Quote:
The really interesting thing to me is that most people (and please understand I'm not picking on you) make assumptions about what I do. I get a sense from phone calls and emails a lot of people think that I use stand alone factors in a vacuum... that as soon as I discover a promising new factor that meets the criteria I posted that I'll start betting that factor as a stand alone.
Personally, I love using single factors (or combos of esoteric factors) in a vacuum, although I use oddsline-based approaches as well. You talked about workouts. I posted a long while back about how I had made a flat-bet profit model using just info from workouts with no other factors. No one believed me because workouts aren't "accurate" and even if they were you've got to consider other factors. You've just GOT to. (Those who insist that "inaccurate" = "useless for making money" really don't understand the game they are playing, IMO.) Certain trainer and pedigree plays have huge ROIs and to look at other factors just seems to dilute them because they make the most when they don't seem to have anything else going for them. I find it actually isn't that hard to come up with flat-bet profitable angles that are based on weird things as long as you can live with low win percentages (10-15%).


Quote:
I've invested a ton of my own man hours into the never ending quest to develop better and better odds lines. No matter how accurate an odds line I make in terms of predicting race winners... and as mentioned I am able to do that with a very high degree of accuracy.... one fact remains: Whenever I simulate flat win betting EVERY horse that goes to post at odds higher than that indicated as a theoretical break even point by the odds lines I create I lose significant money.
I got to the point where on could make an oddsline better than the public (slightly) on any measure you'd care to use to determine that. But they didn't provide many betting opportunities, so I gave that up and now make them differently. They do provide a profit at the theorhetical break-even point and above, but only if I stick to the "contenders". I've never been able to make a full oddsline and have the low probability "overlays" make money. (Although when using spot plays I often bet outrageous long shots and win.) When betting from an oddsline, I restrict play to those where I assign a probability of above average for the field, which is always (1/field size). i.e. in a 5 horse race I need at least a horse assigned 20%, but in a 10 horse race 10% is ok.



Quote:
1. I suck at making odds lines.
2. The pools are pretty efficient by nature.
I have found that making oddslines is one of the great mysteries of life. Jeff, you might want to try the following. If you've got a model, that model is made up of factors that you use as inputs, and then the model spits out a probability value, or something you convert to one. Now, some factors are presumably "more important" to the model than others -- it gives them more weight. And also presumably, you test your models on out-of-sample data and see how they do. Now, take one your "important" factors, and when running a test replace the true values for that factor with random values (in the correct range for that factor), or just scramble the values for that factor in each race (have horses swap values). Compare your randomized test with the true test. As long as you don't use the public odds as one of the random factors, and as long as your model isn't giving a hugely disproportionate weight to that factor (I'm presuming your model doesn't have any one factor that totally dominates), there is a great chance you'll find the randomized tests done in this way perform BETTER than using the actual factor values MORE than half the time. How important is your factor now? Welcome to data mining bias...



Quote:
In practice I find that when I create spot plays keyed off of combinations of hidden positive angles and run those against the odds line theoretical break even point in play or pass decision making... THAT approach consistently wins money.
I would really like for you to elaborate on this -- "keyed off" of how? And the break-even point is determined how? Are you saying you are using your oddsline as-is, but only considering horses for betting that pass some additional factor filter?
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Old 08-20-2007, 10:50 PM   #25
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GT, you wrote:
Quote:
I got to the point where on could make an oddsline better than the public (slightly) on any measure you'd care to use to determine that. But they didn't provide many betting opportunities, so I gave that up and now make them differently. They do provide a profit at the theorhetical break-even point and above, but only if I stick to the "contenders". I've never been able to make a full oddsline and have the low probability "overlays" make money.
It looks like your experiences with odds lines are almost exactly the same as my own. I've also found that when I stick to contenders (which by my own definition are horses with hidden positives) I can make money simply by applying a theoretical break even point provided by an odds line for play or pass decision making.

You also posted:
Quote:
I would really like for you to elaborate on this -- "keyed off" of how? And the break-even point is determined how? Are you saying you are using your oddsline as-is, but only considering horses for betting that pass some additional factor filter?
Yes. That's exactly what I'm saying.

I'm going to use a really simple model to illustrate this. In this case, "keyed off of how" is a simple UDM or spot play defined by the following 2 rules:

1. The horse must be ranked 1st in its field for Power Rating

2. The horse must qualify according to the rules in Boxcar's "B Angle" as set forth in his post from a year or two ago.

OMG I can already hear the flood of groans out there in cyberland.

But let's use THAT as an example of a working UDM and let it define whether or not a horse qualifies as a potential play.


Now, what I've done next is run that against all horses in my calendar year 2006 database broken out by OR3. Before we go any further I need to define OR3. In JCapper, OR3 stands for Odds Ratio Three or Post Time Odds divided by the program's JPRTote Odds Line. In a perfect world OR3 = 1.00 represents a theoretical break even point. Any horse with OR3 >= 1.00 represents an overlay and any horse with OR3 < 1.00 represents an underlay.

Next question: Wha does the data show?

Code:
    Data Window Settings:
     999 Divisor

     Filters Applied: ANGLE_B=   (require Angle B)

     Surface: (ALL*)  Distance: (All*) 
     From Index File: D:\2007\Q1_2007\pl_JPR1_06.txt)


     Data Summary         Win     Place      Show
     Mutuel Totals    3414.00   3328.90   3164.10
     Bet             -3324.00  -3324.00  -3324.00
     Gain               90.00      4.90   -159.90

     Wins                 434       744       943
     Plays               1662      1662      1662
     PCT                .2611     .4477     .5674

     ROI               1.0271    1.0015    0.9519
     Avg Mut             7.87      4.47      3.36


     By: OR3

     >=Min       <Max      Gain       Bet       Roi   Wins  Plays     Pct   Impact
   -999.00       0.00      0.00      0.00    0.0000      0      0   .0000   0.0000
      0.00       0.10      0.00      0.00    0.0000      0      0   .0000   0.0000
      0.10       0.20      0.00      0.00    0.0000      0      0   .0000   0.0000
      0.20       0.30     -4.00      4.00    0.0000      0      2   .0000   0.0000
      0.30       0.40      5.00     18.00    1.2778      8      9   .8889   3.4040
      0.40       0.50      9.00     52.00    1.1731     20     26   .7692   2.9458
      0.50       0.60    -11.10    114.00    0.9026     27     57   .4737   1.8140
      0.60       0.70    -66.90    200.00    0.6655     32    100   .3200   1.2254
      0.70       0.80    -20.20    342.00    0.9409     57    171   .3333   1.2765
      0.80       0.90    -13.50    454.00    0.9703     69    227   .3040   1.1640

      0.90       1.00     18.60    486.00    1.0383     69    243   .2840   1.0874
      1.00       1.10     40.30    458.00    1.0880     58    229   .2533   0.9699
      1.10       1.20      9.30    356.00    1.0261     34    178   .1910   0.7315
      1.20       1.30      3.60    260.00    1.0138     21    130   .1615   0.6186
      1.30       1.40    -40.70    180.00    0.7739     15     90   .1667   0.6382
      1.40       1.50     14.20     90.00    1.1578      6     45   .1333   0.5106
      1.50       1.60     -6.80    100.00    0.9320      5     50   .1000   0.3829
      1.60       1.70     34.40     64.00    1.5375      5     32   .1562   0.5984
      1.70       1.80     24.80     34.00    1.7294      2     17   .1176   0.4505
      1.80  999999.00     94.00    112.00    1.8393      6     56   .1071   0.4103

Now, the UDMs I use in real life work a lot better than the overly simple model I've used here. But the way I use them - and my process in getting there - is almost identical to what I've shown here. Each UDM or model will have its own break even point for OR3 (and other odds ratios within the program.) In the end my play or pass decision making comes down to just 3 things:

1. Does the horse qualify according to the rules of an active UDM or model?

2. Does the horse look ok on the track (my subjective view.)

3. Does the horse have odds high enough to be above the model's break even point for a significant odds line ratio? Which BTW can even be part of the model itself.

If the answer is yes to all three, chances are I'm betting.

GT, in a nutshell... without going into any great detail about the actual factors in my models... that's what I do.


-jp

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Old 08-21-2007, 01:03 AM   #26
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Jeff:

Thanks so much for a marvelously thorough and informative response.

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Old 08-21-2007, 06:26 AM   #27
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Help me to understand impact values, something I had never heard of until joining this forum. Evidently I have been using IV without knowing it for years or maybe I just play an angle. Tell me an approximate IV for my process.

I use the Bris custom card feature and scan an average of 50 or so races per day. I look for a particular factor which takes about 10 seconds per race. Out of 50 races which would be an average of 400 or so horses I may find 2 horses with said factor. Many days there are none and some days there are 4 or 5 so I don't know the actual average but I'm guessing at 2 per day. At the end of a month there may be 40-60 plays and these average 25% or more winners at an average mutual of 10/1. So what would be the IV of my angle?
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Old 08-21-2007, 07:45 AM   #28
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Originally Posted by Pell Mell
Help me to understand impact values, something I had never heard of until joining this forum. Evidently I have been using IV without knowing it for years or maybe I just play an angle. Tell me an approximate IV for my process.

I use the Bris custom card feature and scan an average of 50 or so races per day. I look for a particular factor which takes about 10 seconds per race. Out of 50 races which would be an average of 400 or so horses I may find 2 horses with said factor. Many days there are none and some days there are 4 or 5 so I don't know the actual average but I'm guessing at 2 per day. At the end of a month there may be 40-60 plays and these average 25% or more winners at an average mutual of 10/1. So what would be the IV of my angle?
From "The Handicappers Condition Book" by James Quinn pg 18, "The probability of winning equals simply the percentage of winners having a characteristic divided by the percentage of starters having the characteristic."

So in your case (assuming each race you are talking about only has 1 horse with your factor) with 50 races with 8 horses in the field per race (my guess) that gives you 50 horses with your factor and 400 horses total. So 50 divided by 400 equals 12.5% of starters have that factor. If your horse wins 25% of the time then 25 divided by 12.5 equals 2 or an Impact Value of 2 which is 100% more than would be expected. ( A value of 1 would mean that the factor is not significant either way. If you had Aunt Millie randomly guess the winner by picking just names she liked she would probably have been correct between 12 and 13% of the time. A factor can produce a negative expectation also for example (from the book) 1st time starters over all lose more than would be expected from their percentage of starters.
You sound like you are on to something good but check the link to Gordon Pine's article, it goes more in depth and confuses me a bit!!!
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Old 08-21-2007, 08:03 AM   #29
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Handicapping within angles

Quote:
Originally Posted by Overlay
The only factors I would use as stand-alone angles like that (that would not apply to all horses in a field) are those that would be sufficiently strong that they would statistically qualify as independent variables (such as the type Quirin discussed in Winning at the Races), that by themselves account for the winning percentages they produce, apart from any other variables or factors that might be present in the horse's record. Even then, though, I think there has to be consideration of the angle's winning percentage in light of the horse's odds, rather than just betting any particular angle blindly.
I use seven angles as screens to find live longshots. Then I handicap the strength of the field and other factors, workouts, trainer stats, distance, etc. Jockey, weight, and beyer speed figure are not involved in the process. After this it's go or no go.
For example, freshened fillies are one of my screens and I passed on a 75-1 winner at Calder yesterday because the other factors did not confirm a play. I did catch one at the same odds a few years ago because both the class of the race and workouts confirmed it. Despite missing an odd win here or there, the extra step has produced positive results.
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Old 08-21-2007, 08:41 AM   #30
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Originally Posted by nobeyerspls
I use seven angles as screens to find live longshots. Then I handicap the strength of the field and other factors, workouts, trainer stats, distance, etc. Jockey, weight, and beyer speed figure are not involved in the process. After this it's go or no go.
For example, freshened fillies are one of my screens and I passed on a 75-1 winner at Calder yesterday because the other factors did not confirm a play. I did catch one at the same odds a few years ago because both the class of the race and workouts confirmed it. Despite missing an odd win here or there, the extra step has produced positive results.
I'd be interested in hearing more about the "freshened fillies" filter. I think that when a f or m goes sour, they just don't seem to get back without a break and i noticed this from the owners side first but then picked up on it from the handicapping side as well. do you see any difference with respect to age ?

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