New PPA seedings out - Dec 2013

[Skubarra]

Seeding doesn't seem to be reflecting on PPA for my recent results...

 

Only the road seeding have been updated, not mtb?

[Aaron_B]

Neither road nor MTB is reflecting my side. Will try again later.

['Dale]

Only the road seeding have been updated, not mtb?

 

PPA

Only the road seeding have been updated, not mtb?

 

PPA often prioritise road seedings in spring / summer and the same for MTB in autumn / winter

[WKNDWRRR]

These PPA seedings are an absolute lottery.

 

How does the Durbanville High School fun ride have a beta of 1.05 and Die Burger 0.98? It was a shorter distance, less elevation and near perfect weather conditions.

 

My sentiments exactly, it doesn't make sense to me.

[Pieterg]

link please

[WKNDWRRR]

link please

 

http://www.pedalpower.org.za/index.php/results-seeding/seeding/

[Pieterg]

thanks

[andydude]

Die Burger should almost be an index of 2 (or so) for you right? Nicely done!

 

After a shaky start (and broken bike), I am back into the group in which I was seeded at the beginning of the season. YAY!

 

Didn't do much, but yes, 1.88

 

I see they didn't adjust Johann's winning time.

[andydude]

My sentiments exactly, it doesn't make sense to me.

 

What doesn't make sense? Maybe we can try to help?

[DJTerblanche]

These PPA seedings are an absolute lottery.

 

How does the Durbanville High School fun ride have a beta of 1.05 and Die Burger 0.98? It was a shorter distance, less elevation and near perfect weather conditions.

That's what I mean by lottery.

 

The PPA's beta Calculation seems more mathematical than "lottery" to me.

Question of how good the equation is that they are working with, is another topic.

But I am sure they will be open to help from anyone who think they can improve on it.

 

The beta is basically calculated by comparing other base events to the most recent one, comparing the performance of all the people who did the same ride and deriving a beta from that which should theoretically be an approximation of how difficult a course was.

 

I think windy condition might throw this calculation off for the average cyclist.

Let's say most of the good and elite riders sat in nice big bunches and worked together efficiently to combat the wind.

While perhaps the moderate cyclists might have been scattered all over the show, jumping groups and groups being split by side winds and/or inexperienced / selfish riders who lets the guy pulling tire out and not giving him rest by also helping to pull. This might make the race much more "difficult" for the moderate cyclist in windy conditions. This is just my 2cents.

 

Here is an extract from the PPA website.

 

http://www.pedalpower.org.za/index.php/results-seeding/seeding/how-we-calculate-your-seeding/

3. For each ride, adjust the winner’s time and calculate the difficulty (beta)

Some races have a better quality of field than others. For instance, some events may have visiting pro riders participate and some events (especially shorter routes) have no top riders present. So we adjust the winner’s time to take this into account.

It would also be unfair to get the same seeding for being the same percentage behind the winner in a fast, flat ride as in a hilly, difficult ride. To allow for this we calculate a difficulty or “beta” factor. This makes the gap between the winner and you count less in difficult conditions and more in easy conditions.

First, an extract is done of all the riders who did the event in question, as well as the base event. Every rider with an index better than 100 is taken for this calculation. The assumption is made that the same riders should have the same index for both events, so the winner’s time of the funride is now adjusted and the “beta” is calculated to achieve this.

In statistical terms, a linear regression is performed for the event relative to the indexes of the people in the event who also rode one of the base events. This determines how much the winner’s time should be adjusted and what the difficulty factor “beta” should be. There is no subjectivity in this process – it is an automated calculation without human intervention.

In layman’s terms, the adjusted winner’s time should be roughly the time that the winner of an event would have done if the winner of the Cycle Tour had ridden that event at the same effort. The beta factor will be 1 if the event is as difficult as (i.e. on par with) the Cycle Tour, less than 1 if it is easier (eg flat and fast), and more than 1 if it is harder (eg hilly or very windy)

[andydude]

The PPA's beta Calculation seems more mathematical than "lottery" to me.

Question of how good the equation is that they are working with, is another topic.

But I am sure they will be open to help from anyone who think they can improve on it.

 

The beta is basically calculated by comparing other base events to the most recent one, comparing the performance of all the people who did the same ride and deriving a beta from that which should theoretically be an approximation of how difficult a course was.

 

I think windy condition might throw this calculation off for the average cyclist.

Let's say most of the good and elite riders sat in nice big bunches and worked together efficiently to combat the wind.

While perhaps the moderate cyclists might have been scattered all over the show, jumping groups and groups being split by side winds and/or inexperienced / selfish riders who lets the guy pulling tire out and not giving him rest by also helping to pull. This might make the race much more "difficult" for the moderate cyclist in windy conditions. This is just my 2cents.

 

Exactly. And it's not necessarily bad if the calculation is somewhat off with windy races, because the same riders riding "alone" will then still be batched together.

 

I think the bigger problems are clubs and groups riding in seedings worse than their own and then pulling the whole bunch along. This really messes up the seeding for everyone after the first few racing bunches.