Accommodating late check-ins

Debates and discussions on the various race scheduling methods that can be used and their fairness and accuracy in determining the winners.
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Jeff Piazza
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Accommodating late check-ins

Post by Jeff Piazza » Mon May 19, 2014 8:44 am

If you've run more than a few derbies, you've almost certainly had the experience of having to deal with a late arrival (or, worse, an on-time racer whose presence wasn't immediately recorded) for a group (den) that's already started, but not completed, racing. There are cases where such a racer may or should be turned away, but for this discussion, let's assume that the goal is to include the racer in with his group, to the greatest extent possible.

I've seen the advice that such a case should be handled by adding manual heats (in GPRM) in which the late arrival races alone in each lane. That's not a bad answer, but I've been thinking lately about how to do better.

In particular, in a one-heat-per-lane-per-racer chart, if the number of heats remaining is at least (number of lanes - 1), then the late racer could be accommodated by adding just one extra heat (so there are now at least number-of-lanes heats remaining), and then, for each lane, picking one heat for the new racer to appear in that lane. The previously-scheduled racer displaced by the new racer then populates the new (last) heat, without changing lanes. (If the new racer gets placed in the last heat, then there's no one to displace for that lane, obviously.) This strategy produces (number-of-lanes) x (number-of-heats-remaining) possible charts, which isn't a whole lot (if you're a computer), so each can be practically generated and evaluated for equality of opposition, or any other criteria you'd like.

If you start from a partial perfect chart, the result unfortunately need not be partial perfect (even if your search criteria prefers it); it's pretty easy to find examples. However, the difference between the greatest head-to-head matchup count and the least head-to-head matchup count in the chart increases by no more than 2 (for a single-round chart). I suspect but can't yet prove that the increase can be kept to 1, but I also haven't explored a lot of examples yet.

Another interesting strategy is to try renumbering the cars from the heats that have already been run, in such a way that those heats can be incorporated directly as ppn heats for the larger field. Obviously this isn't always possible, but gives a better result when it is possible.



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Stan Pope
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Re: Accommodating late check-ins

Post by Stan Pope » Mon May 19, 2014 10:53 am

Jeff Piazza wrote:...
I've seen the advice that such a case should be handled by adding manual heats (in GPRM) in which the late arrival races alone in each lane. That's not a bad answer, but I've been thinking lately about how to do better.
This is a great topic! I'll look at it in more detail tonight.

However, the above work-around IS a bad answer. The reason is that a car running alone almost always runs faster than the same car running with competition! Causes? several possible.

My "first blush" answer is to include a percentage of "dummy racers" in the original PPN chart. When/if late racers arrive, each is assigned to one of the dummy dummy racers. At the end, you can rerun the heats which are now incomplete. For fairness, only the late arrival's time should be used ... the other racers in the heat should retain their original heat times. (Yes, I know that few race management programs support this without a lot of "fiddling".)


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FatSebastian
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Re: Accommodating late check-ins

Post by FatSebastian » Mon May 19, 2014 11:28 am

Stan Pope wrote:a car running alone almost always runs faster than the same car running with competition!
I'd be curious to know by how much. Has anyone ever quantified this?



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Re: Accommodating late check-ins

Post by knotthed » Mon May 19, 2014 11:53 am

The first step in our Derby is to enter the complete roster into GPRM about a week before the event. Then you can not pass the no shows and exclude them from the schedules. We also have a "Last Call" for anyone who hasn't checked in, before creating the schedules.

I think a well defined and regimented checkin process will help prevent this.

I would agree with Stan, I would not let the car run by itself.

I know of an example where a car was missed in a race, the official then created a new race/heat. But had two substitute cars run against it to simulate a real scenario.

Faster cars will run faster together and slower cars can slow others.



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Stan Pope
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Re: Accommodating late check-ins

Post by Stan Pope » Tue May 20, 2014 8:18 pm

There are at least two groupings of late arrival situations that should be considered. One is typical of packs, where you know within a small number who and how many racers are likely to show up to race. Late arrivals are possible, but not so likely. This situation is manageable with a variety of fixed schedules such as PPN. Schedule all of them and let them join as they arrive. You may penalize late arrivals or not by whether or not you rerun their missed heats to get them times.

The other grouping is more difficult. It is a typical district or council race in which advance registration is encouraged, but you are subject to substitutions, missing registrants, walk-ins, and late arrivals. Since the race venue may be new to many or most of those attending, it is certainly reasonable to allow entry of late arrivals. Some penalty for late arrival is reasonable, but it should be proportional. This is why I like methods like quintuple elimination (QE) or, better, Burlington 15th for this kind of race. Late arrivals for QE get a loss recorded for missed heats, so arriving an hour late, for instance, might be racing first with the group that has 2 losses and no wins. He can still finish 1st if his car is really good, but he has little margin for error.


Stan
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