Great discussion! I do apologize in that I was not thinking about all the awards NADAC has tied to DRI in my original post. I can see how any change in the calculation could ruffle some feathers. My current dog is fast but he is not a regular member of the 100+ DRI club. It makes no personal difference to me whether the 100 DRI is based off of the top 5% or off of the top 10%. What does make the DRI such a powerful tool is that it is based off of the fastest runs. Chances are that the vast majority of the 100+ DRI runs did not have any off courses or bobbles or missed weave entrances. It gives me a clear marker of what the best teams can accomplish. It is something I cannot get with only data from my dog - with lots of off courses and bobbles and missed entrances. My goal for the post was only to improve the tool for Weavers where I thought distance had a strong influence on the current DRI calculation and really diminished its power. I agree with Ed that the numbers Chris posted seem to support the influence of distance on the Weavers DRI.
As Chris stated, the easiest way to fix the problem would be make all of the Weavers courses the same length. My guess would be if the courses were all within a range of 25 yards, the distance influence on the Weavers DRI would probably be +/-2 or 3 from the average. Or to state differently, the same run on the shortest allowed course might have a DRI of about 5 less that of the longest allowed course. But that is only an estimate based on my proposed formula that uses the Tunnelers DRI 100. As others posted, that might not be the perfect DRI 100 to use because there could also be Hoops.
I was amazed at how fast Chris came back with the various statistics from the DRI calculations. All the data must already be in easily manipulated spreadsheet form? If that is true, there would be no need to use a formula like I originally posted. The rest of this post is just a proposed alternative way to calculate a Weavers DRI without a distance influence if that is the decided path. This alternative DRI would also help get the desired percentage of dogs with a 100 DRI+ regardless of course length. If you like the math, continue reading. If not, don't worry about the rest of this post.
If you have all the yps data with the length of each associated run, I would make two Excel columns - one for yps and the second for the associated run length. I would sort the data together on run length. Depending on how much data I had, I would break the data up into set run length increments (maybe 100-105, 106-110, 111-115, etc). I would then sort each of those increments on yps. I would take the top percentage ("top" being whatever I wanted the DRI 100 based on) and average for the DRI 100 for each increment. I would then do a best fit with DRI 100 on the y-axis and run length on the x-axis. (If a good best fit is a horizontal straight line, then you have proved there is no distance impact on DRI. I highly doubt that will be the case. You might need a second order fit.) All this work is a one time (or maybe every few years) deal. Once you have the equation of the line, you just put it in another excel speadsheet. Then for each course you could just enter the course length into the equation and it will calculate the adjusted DRI 100 for that course.
Arne
