Rennpoints predictions
12-11-2014, 08:30 PM
#1
Perfect Angel
Rennlist Member
Rennlist Member
Thread Starter
Rennpoints predictions
Maybe one of you other racer types can explain this to me. For the last two years I have not been getting a predicted lap time listed. And when I goto the driver page and get lap time predictions they are slower than my actual lap times. For example, at Summit Point the predicted lap time is 1.5 seconds slower than my actual time.
Is there a setting in RP or MyLaps that I need to fiddle with?
Is there a setting in RP or MyLaps that I need to fiddle with?
12-11-2014, 08:46 PM
#2
12-11-2014, 08:48 PM
#3
Rennlist Member
It will not give a prediction if your predicted time is slower than your actual time. It's as if the program thinks you over-achieved and should not have gone that fast... and it doesn't want to publicly humiliate you.
Why it sometimes thinks that is a mystery to me... The predicted lap times have always been a mystery to me. And clicking on the "prediction" formulation does little to clear it up.
Why it sometimes thinks that is a mystery to me... The predicted lap times have always been a mystery to me. And clicking on the "prediction" formulation does little to clear it up.
12-11-2014, 10:41 PM
#5
Rennlist Member
I love and appreciate Rennpoints, but there is some strange flaw in the computer program. My predicted time is often pretty accurate, however the program plays favorites. There are two people who are always predicted much faster than me... even though they are never actually faster than me in the real world. They know who they are because it's become a joke between us.
They must be on the Rennpoints Board of Directors.For the Road America race last year, there was some random guy who was predicted to blow Doug Crossman's doors off by several seconds a lap in G class. That was worth a good laugh.
12-12-2014, 12:21 AM
#6
Maybe one of you other racer types can explain this to me. For the last two years I have not been getting a predicted lap time listed. And when I goto the driver page and get lap time predictions they are slower than my actual lap times. For example, at Summit Point the predicted lap time is 1.5 seconds slower than my actual time.
Is there a setting in RP or MyLaps that I need to fiddle with?
Is there a setting in RP or MyLaps that I need to fiddle with?
12-12-2014, 11:21 AM
#7
Rennlist Member
I have wondered the same thing before about it being out for some and not others. I did some looking around and what I noticed is that it averages lap times between you and another like competitor. This mostly works unless there isn't great consistency in the lap times between either you or the person it compares you to. Averaging the result then just amplifies the problem. Kinda how the average of 1 and 15 is 8, which is not even close to either 1 or 15.
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04-20-2015, 05:14 PM
#13
The prediction algorithm is a bit involved...
It started with something that a buddy and I noticed a long time ago that our lap times relative to the class records tended to be very consistent. I.e, if my lap time at a track is 1.05x the class record, it is likely to be 1.05 times the class record at most other tracks (usually within 2/10s of a percent).
In the first incarnation of coming up with predictions, I tried to apply that formula and ran into a few basic problems.
1) If an event is lightly attended and a "slow" driver puts up a class record due to poor competition showing up, the prediction for that driver tends to greatly overstate how good they will do at future events.
2) Since the comparison is made against the track record, the best that you could be predicted to do is as good as the track record.
3) If your first couple events are at rainy events, it will generally give you poor predictions as it sees that you are driving slow (compared to the class records)
I thought about this for a while and came up with a new comparison mechanism that resolved a few of those issues
1) The algorithm looks at all sessions that you ran against other people in your class and that have also raced at the track that we are trying to predict. It assumes that the ratio between your lap times will stay constant. For example, if at another track, you turn a 61 second lap, and your peer turned a 60 second lap, it assumes that ratio stays constant. So, if your peer turned a best of a 120 second lap at the prediction track, it assumes you will turn a best of 122 seconds.
By comparing racers at the same session, it nicely solves the problems of weather conditions (as both people see the same conditions). It also allows the prediction to be faster than the standing class record.
Now, the problem remaining is which driver to compare against and which of your sessions should it use as the base? I.e., we want to generate a prediction based on when you were running a good lap time (e.g., no car issues) and your peer was also running a good lap time. For that, we compare your lap time against the class record and your peer's time against the track record. Also, to ensure that your competitor is consistent, we compare his best lap time at the prediction track against the track record. We look for instances where all three comparisons are close to the track record.
As a formula, we are trying to maximize the following:
(class record at comparison track)/(your lap time at comparison track) * (class record at comparison track)/(your peer's lap time in same run session at comparison track) * (class record at prediction track / your peer's best lap time at prediction track)
Once we find that number, we then look for other peers within 2% of that product. We then use the ratio of lap times to come up with predictions and average them all together.
I've found that the prediction is remarkably accurate but am aware there are a few flaws:
1) If somebody did really well a long time ago, it still keeps coming up with good predictions for that person. I should have something that ages out old results
2) Class records are always based on the current class record. It may be worthwhile to use the class record as it stood at the time (that might also solve the above problem)
Hope that helps clear things up...
It started with something that a buddy and I noticed a long time ago that our lap times relative to the class records tended to be very consistent. I.e, if my lap time at a track is 1.05x the class record, it is likely to be 1.05 times the class record at most other tracks (usually within 2/10s of a percent).
In the first incarnation of coming up with predictions, I tried to apply that formula and ran into a few basic problems.
1) If an event is lightly attended and a "slow" driver puts up a class record due to poor competition showing up, the prediction for that driver tends to greatly overstate how good they will do at future events.
2) Since the comparison is made against the track record, the best that you could be predicted to do is as good as the track record.
3) If your first couple events are at rainy events, it will generally give you poor predictions as it sees that you are driving slow (compared to the class records)
I thought about this for a while and came up with a new comparison mechanism that resolved a few of those issues
1) The algorithm looks at all sessions that you ran against other people in your class and that have also raced at the track that we are trying to predict. It assumes that the ratio between your lap times will stay constant. For example, if at another track, you turn a 61 second lap, and your peer turned a 60 second lap, it assumes that ratio stays constant. So, if your peer turned a best of a 120 second lap at the prediction track, it assumes you will turn a best of 122 seconds.
By comparing racers at the same session, it nicely solves the problems of weather conditions (as both people see the same conditions). It also allows the prediction to be faster than the standing class record.
Now, the problem remaining is which driver to compare against and which of your sessions should it use as the base? I.e., we want to generate a prediction based on when you were running a good lap time (e.g., no car issues) and your peer was also running a good lap time. For that, we compare your lap time against the class record and your peer's time against the track record. Also, to ensure that your competitor is consistent, we compare his best lap time at the prediction track against the track record. We look for instances where all three comparisons are close to the track record.
As a formula, we are trying to maximize the following:
(class record at comparison track)/(your lap time at comparison track) * (class record at comparison track)/(your peer's lap time in same run session at comparison track) * (class record at prediction track / your peer's best lap time at prediction track)
Once we find that number, we then look for other peers within 2% of that product. We then use the ratio of lap times to come up with predictions and average them all together.
I've found that the prediction is remarkably accurate but am aware there are a few flaws:
1) If somebody did really well a long time ago, it still keeps coming up with good predictions for that person. I should have something that ages out old results
2) Class records are always based on the current class record. It may be worthwhile to use the class record as it stood at the time (that might also solve the above problem)
Hope that helps clear things up...
04-20-2015, 05:36 PM
#14
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Brian, I also notice that you are not carrying forward GTS times as class records and are only showing class records for GT classes for the last year or so since the combination of S and R into one class.
For a number of tracks, that means that the GT class records a slower than the previous records for GTS, and at some tracks, significantly slower.
I understand that you don't want to show the old GTR class records as current records, since GT cars running slicks now have to run 50 lbs heavier than the street tired cars in their class, whereas they were running the same weight, S and R, before but wouldn't it make sense to show GT class records from before, if the GTS class record was faster then was turned last year?
For a number of tracks, that means that the GT class records a slower than the previous records for GTS, and at some tracks, significantly slower.
I understand that you don't want to show the old GTR class records as current records, since GT cars running slicks now have to run 50 lbs heavier than the street tired cars in their class, whereas they were running the same weight, S and R, before but wouldn't it make sense to show GT class records from before, if the GTS class record was faster then was turned last year?
04-20-2015, 05:43 PM
#15
Brian, I also notice that you are not carrying forward GTS times as class records and are only showing class records for GT classes for the last year or so since the combination of S and R into one class.
For a number of tracks, that means that the GT class records a slower than the previous records for GTS, and at some tracks, significantly slower.
I understand that you don't want to show the old GTR class records as current records, since GT cars running slicks now have to run 50 lbs heavier than the street tired cars in their class, whereas they were running the same weight, S and R, before but wouldn't it make sense to show GT class records from before, if the GTS class record was faster then was turned last year?
For a number of tracks, that means that the GT class records a slower than the previous records for GTS, and at some tracks, significantly slower.
I understand that you don't want to show the old GTR class records as current records, since GT cars running slicks now have to run 50 lbs heavier than the street tired cars in their class, whereas they were running the same weight, S and R, before but wouldn't it make sense to show GT class records from before, if the GTS class record was faster then was turned last year?