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5K distance variation (Read 1825 times)


I've got a fever...

    That seems silly. The requirement should be that a certified 5k course is exactly 5000 meters. Why go through the cost and the trouble if there is still a fudge factor?
    I can never tell when you're serious or not. This is just in case there is a small screw-up. They err on the side of caution, because if a record is set on a course that's found to be even a little short, it doesn't count. And you don't want to be that course owner.

    On your deathbed, you won't wish that you'd spent more time at the office.  But you will wish that you'd spent more time running.  Because if you had, you wouldn't be on your deathbed.

      I can never tell when you're serious or not.
      My second reply was the serious one. To me, it's just as unacceptable to be long as it is to be short so I don't understand how a competent certifier can have a small screw-up. If you certify a course I would be disappointed if they only claim that the course is at least 5k (or whatever the distance). I would hope that they would ensure that the course, as measured, is exactly the distance they claim. This fudge factor boggles my mind. Now, again, that doesn't mean that a runner will run all the tangents perfectly and be able to run the course as certified but that's not the problem of the course certifier. MTA - Oh...and if you couldn't tell I have absolutely no experience in course certification but why would I ever let my lack of experience get in the way of an opinion?
      "Good-looking people have no spine. Their art never lasts. They get the girls, but we're smarter." - Lester Bangs


      A Saucy Wench

        My second reply was the serious one. To me, it's just as unacceptable to be long as it is to be short so I don't understand how a competent certifier can have a small screw-up. If you certify a course I would be disappointed if they only claim that the course is at least 5k (or whatever the distance). I would hope that they would ensure that the course, as measured, is exactly the distance they claim. This fudge factor boggles my mind. Now, again, that doesn't mean that a runner will run all the tangents perfectly and be able to run the course as certified but that's not the problem of the course certifier. MTA - Oh...and if you couldn't tell I have absolutely no experience in course certification but why would I ever let my lack of experience get in the way of an opinion?
        Because ALL measurement tools have error. All.Some have more, some have less. Fudge factors are introduced to make sure that all error falls on the "acceptable" side. In this case long, not short for the reason that Jeff mentioned. When you buy packaged good that are sold by weight the fudge factor is so that you are always sold a bit more, never a bit less -the specification is usually along the lines of 20 oz +2/-0 and the filling station is actually set for 21 oz Certified races there is a published spec. Un certified races by experienced groups who dont want to pay for certification are generally not that much different Local "raise money for the flavor of the month" races that are run by people who have seen a race flyer once can be off by quite a bit. I wouldnt be surprised at 10% MTA: The ustaf certification fudge factor is 1.001 so 5K will MEASURE at least 5005 meters. Courses must be measured at least twice and the shortest distance recorded. So if you measure 5005 and 5004, they gotta move it out another meter. But the course must have 2 measurements within 0.08% of eachother to be certified, the lowest of which measures 5000*1.001=5005. So it is possible to be as high as 5009.004 meters on a certified 5K

        I have become Death, the destroyer of electronic gadgets

         

        "When I got too tired to run anymore I just pretended I wasnt tired and kept running anyway" - dd, age 7

          Nice work Ennay and thanks for the research. That certainly looks like you know what you're talking about and I learned something new. I'm still boggled/disappointed by the fact that certifiers can't get the distance exactly correct and they build in a 0.1% factor admitting as such. Oh well. It's not material and if every course has the same criteria it's fair.
          "Good-looking people have no spine. Their art never lasts. They get the girls, but we're smarter." - Lester Bangs


          A Dance with Monkeys

            I am boggled that one could expect a human to measure road distances to within 0.1%...
              I am boggled that one could expect a human to measure road distances to within 0.1%...
              Yeah. I can understand that and I've received some education. But a meter is a meter. So why can't 5000 meters equal 5000 meters? Like I said, it's immaterial and is only interesting (most likely) to me.
              "Good-looking people have no spine. Their art never lasts. They get the girls, but we're smarter." - Lester Bangs
                Yeah. I can understand that and I've received some education. But a meter is a meter. So why can't 5000 meters equal 5000 meters? Like I said, it's immaterial and is only interesting (most likely) to me.
                If you want it exact run a track? Even then are you running the inside of the track or the outside... O well I tried... I know we are in the 21 century but we still aren't exact!


                ultramarathon/triathlete

                  But a meter is a meter. So why can't 5000 meters equal 5000 meters? Like I said, it's immaterial and is only interesting (most likely) to me.
                  In this day and age, there's no reason a certified course should not be spot-on. We should expect no less than perfection when we're paying for it, especially given the tools at our disposal. If they measure a course twice and get different measurements, they should go back out and measure it two more times and do so until they get it right. I, for one, am going out to beat my last best time. If the course is wonky, how's that fair to anyone? Now, I realize some people don't care about the numbers, they have a variety of other reasons to race or run, but that's not all of us.

                  HTFU?  Why not!

                  Coach: Empire Tri Club 

                  Speed Coach: Brooklyn Tri Club
                  USATF Coach

                    If they measure a course twice and get different measurements, they should go back out and measure it two more times and do so until they get it right.
                    If they were to go back and measure it "two more times" they would just get two more measurements and it's possible, and likely, that neither would read 5000 meters. Note that I didn't say 5000.0m or 5000.00m or 5000.000m because that implies ' precision'. 5000m is EXACT. There is no way on this Earth to measure anything EXACTLY! We live in a world where engineers manage these measurement errors so well you don't even notice them. Go re-read Ennay's post about measurement error.


                    I've got a fever...

                      Folks, there is no such thing as an exact measurement. There is error associated with any and every measurement, though uncertainty is maybe a kinder word, since error has such a negative connotation. Uncertainty is woven into the fabric of the universe -- in quantum theory, there is something known as the Uncertainty Principle:
                      In quantum physics, the Heisenberg uncertainty principle is the statement that locating a particle in a small region of space makes the momentum of the particle uncertain; and conversely, that measuring the momentum of a particle precisely makes the position uncertain. Physically, the uncertainty principle requires that when the position of an atom is measured with a photon, the reflected photon will change the momentum of the atom by an uncertain amount inversely proportional to the accuracy of the position measurement. The amount of uncertainty can never be reduced below the limit set by the principle, regardless of the experimental setup.
                      This means at the atomic level, the act of measurement will actually change what you are trying to measure. Uncertainty is everywhere! But think about it in a practical sense. How do you know that the wheel used to measure a course is exactly perfectly calibrated? You can't, but you usually determine that it's within a tolerance. Maybe one of the machines used to fabricate that wheel was acting a little janky that day, and messed up some of the spacing ever so slightly. Maybe the guy running the machine had a hangover. Who knows? If there is surveying involved in setting up the course, how do you know that the survey scope is exactly correct? You can't, but there's a tolerance. How can you be certain that they picked the exact perfect tangent line? Ennay said above that certified courses are measured at least twice. If the same person used the same wheel to measure the same course 2, 3, 10, or 100 times, they wouldn't get the exact same result every time, because perfect repeatability in the real world is impossible. The best we can do is improve our systems to make the inherent variation acceptable. GPS, as accurate as it is, has some uncertainty. But being within a 10m radius anywhere in the world is considered an acceptable amount of uncertainty for most applications. As an engineer, I have to deal with random variation, uncertainty, repeatability, and tolerances every day. Because I live it, I'm not at all surprised by the use of a fudge factor on course measurement to ensure that is as at least as long as it says. And suppose because I live it, I'm stunned that anyone could expect any measurement anywhere to be perfectly exact. A meter is a meter, right? Well, the original basis for the meter was the length between two marks on a platinum-iridium bar: Since it's impractical to use a metal bar stored in Paris to calibrate instruments all over the world, they eventually settled on a meter as being the distance the speed of light travels in 1/299 792 458 seconds in a vacuum (although the definition evolved over time as technology improved). Okay, so you're sure that the wheel they used to measure the course meets this tolerance, right? Even that metal bar isn't exactly a meter, not as we define it now because it was originally based on one ten millionth of the distance of between the equator and the north pole. Guess what, the earth's not perfectly spherical. That bar is about 1/5 of a mm short of what we call a meter today. And don't forget that if I'm running faster than you, I see time slightly differently than you thanks to special relativity (although the difference is beyond what we can measure). Tongue Remember that when you see a measurement of any kind anywhere, there is a hidden ± sign next to it. Nothing is exact. MTA: I changed the line "Uncertainty is built into...." to "Uncertainty is woven into..." Becaause it sounds more poetic. And because I am a dork.

                      On your deathbed, you won't wish that you'd spent more time at the office.  But you will wish that you'd spent more time running.  Because if you had, you wouldn't be on your deathbed.

                      JimR


                        Jeff summed it all up well. It's neither practical nor likely that one can get a perfect measurement of a course of any length. It's challenging enough engineering a 400 meter track to be 400 meters let alone getting perfect measurements of every curve, rise, bend of every one of thousands of courses which receive certification. And if that course changes even slightly (like having a roadworking crew rebuild a curb), perfection would mean remeasuring after every single change. Everything has a level of error to it. If you want your best time, find the certified courses that consistently produce the fastest times. USATF clearly says they strive for accuracy as best as can be practically attained, but for record keeping purposes they cannot have a course be short. For 99.9% of runners, these are moot points.


                        A Saucy Wench

                          I know see the wisdom of my college that made everyone take measurements lab. Big grin

                          I have become Death, the destroyer of electronic gadgets

                           

                          "When I got too tired to run anymore I just pretended I wasnt tired and kept running anyway" - dd, age 7


                          I've got a fever...

                            I know see the wisdom of my college that made everyone take measurements lab. Big grin
                            But apparently not the wisdom of taking more English classes. Tongue

                            On your deathbed, you won't wish that you'd spent more time at the office.  But you will wish that you'd spent more time running.  Because if you had, you wouldn't be on your deathbed.


                            A Saucy Wench

                              But apparently not the wisdom of taking more English classes. Tongue
                              Shit. I plead mommy brain. I was nursing my son and yelling at dd to get dressed at the same time and having a riveting discussion about why she cant wear a wool sweater to farm camp today when the forecast is 91 degrees. Who needs English anyway?

                              I have become Death, the destroyer of electronic gadgets

                               

                              "When I got too tired to run anymore I just pretended I wasnt tired and kept running anyway" - dd, age 7

                                In all seriousness, this was fascinating to me. I appreciate the lenghty explanation of both Ennay and gObLuE (I read it twice) and you've flipped me. Well done.
                                "Good-looking people have no spine. Their art never lasts. They get the girls, but we're smarter." - Lester Bangs
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