For Chris Eubank Jr, the cost of professional boxing not going metric is £375 000

6 thoughts on “For Chris Eubank Jr, the cost of professional boxing not going metric is £375 000”

1. Every measuring device has a range of uncertainty associated with it. This uncertainty might be entirely positive, entirely negative of a mixture of both. Unless it is specified otherwise, it is normal to assume that the uncertainty is ±Δ/2 where Δ is the smallest interval that can be detected using the device. Once classic case where the uncertainty is always negative is car speedometers – this is to ensure that if you obey your speedometer, you will not inadvertently exceed the speed limit due to instrument uncertainty.

   In the case of Eubank being overweight for his title fight, Eubank (orhis agent) should question the uncertainty of the weighting device. If we assume that the boxing promoters were using a Class III, hospital quality scale, then one can assume that the device could accuracy (Δ) of 0.01 kg up to 100 kg and that the announcer had a look-up chart to convert from kilograms to stones and pounds.

   What sort of things could affect the accuracy of the scale? First of all, devices of this accuracy need to be recalibrated in situ every time that they are used.  There are two different types of weighing machines.

   Firstly, there are those that balance the mass of the object being weighed against a set of calibrated weights. One source of error in these balances is that the accuracy depends on the density of the air being constant. If one uses weights that are made of brass (density typically 8 kg/L) to weight a human body (density typically 1 kg/L), then the human body will displace more air than the weights. With air having a density of about 1.22 g/L, then using Archimedes Principal it can he shown that the human body will experience an upthrust of about 0.122% while the weights will experience an upthrust of one right of this amount due to the having eight time the density.  As long the system’s calibration takes this into account, there will be no problem.  If the device is calibrated at sea level and is then take to a city which is at altitude such as Johannesburg which is at 1600 metres above sea level and the air density drop to 1.04 /L the differene in upthrust is enough to make a 20 g difference for a person weighing 100 kg.  

   The other type of weighing device is electronic and uses a load cell. These devices are even more sensitive to being moved around the globe as they are dependent upon the acceleration due to gravity which varies between 9.78 m/s² at the equator to 9.83 m/s² at the poles  being constant at the timeof calibration adn the time of weighing. AS can be seen the variation can be as much as 0.5%.

   In conclusion then, if the Eubank team wish to challenge his fine in the courts, the boxing promoter will have to show that they took extreme care in setting up their weighing device, otherwise the courts might well rule that the uncertainty in the measurement was greater than 0.05 lbs and therefore the fine will have to be refunded (not to mention that amount of egg on the boxing promoter’s face).

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2. Personally I have less than no interest in boxing, but rules are rules and the threshold defined to the instrument of the day. Tolerances goes both ways, 1 gram inside limits or 1 gram out.

   As in Formula one the limits are strict with no argument, down to a drop of sweat, urine or even a shave. In F1 a couple of weeks ago it was down to a lap of too much tyre wear.

   However, the subject is metric vs imperial (or probably USC in this case), that is a rather pathetic intransigence of the anti metric brigade. We have been through the stupid cricket so-called metric soft conversion, the two inch or something in athletics, a foot somewhere else in a road event, we have to oddity of the definition of space being 50 miles in USA and or 100 km internationally which is not a conversion at all but a very confusing divergence of ideas.

   I think the phrase “the umpires decision is final” seems appropriate here. The human race will never pursue a common definition.

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3. “Tolerances goes both ways, 1 gram inside limits or 1 gram out.”

   If professional boxing used the same standard metric weight categories that are used in amateur boxing, he would have been 2.4 kg within the limit. Tolerances wouldn’t have been an issue in this case.

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4. Something doesn’t seem right here. 0.05 lb is slightly <23 g. All the scales and balances I’ve seen that measure mass in kilograms for large objects never display a number <100 g, showing as 0.1 kg increments on the display. I’m sure even hospital scales are the same way. So, I can’t understand how one can accurately state a mass as fine as 23 g.

   As Martin stated, there is the possibility the boxer was weighed on a hospital grade kilogram scale and the weight converted per a chart. If the scale is calibrated to the nearest 100 g, and the display showed his mass as 72.6 kg, this is 30 g over the limit, which is 0.066 lb and not 0.5 lb. But, the 0.05 lb could have resulted from round off errors when converting or using charts.

   It makes no sense to provide limits to two decimal places in kilograms when the typical scale can’t measure that fine and to continue to base mass ranges in pounds when scales available to measure in pounds exist in only one country is totally insane.

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5. @BrianAC I disagree with you regarding the “Instrument of the day”.  One of the goals of the metrology industry is to ensure that, as far as is possible, different instruments give the same reading when performing the same measurement, but since this cannot be achieved, metrologists have developed techniques whereby the uncertainty of instruments can be catalogued. In my earlier post, I was questioning whether or not the accuracy of the scales used had been properly verified. In the case of Eubank, suppose that there was a set of “unofficial” scales in the changing rooms and he found that he was just over the limit, he might go to the toilet to try to lose a few more grams. If however the “unofficial” scales said that he was within limits, but the “official” ones said that he was over the limit, he would have cause to complain.  

   I would note that in the United Kingdom, it is extremely difficult to get scales that use Imperial units which are professionally calibrated – UK hospital scales (which would be appropriate in this case) are calibrated only in metric units. Thus, if one is using metric scales to work to imperial standards, there is scope for error in the unit conversion. I did a quick internet check on Class III medical scales and found that the sensitivity at 60 kg varied from 20 g, 50 g and eve n100 g! The fact that Eubank was judged to be 0.5 lb over, suggests to me that the scale showed that he was 20 g over and that the scales I use had graduations of 20 g.  

   Finally, you stated that in cricket, “the umpire’s decision is final”. I am a qualified cricket umpire and there are circumstances where the umpire can be held to account in the courts for injuries resulting from him allowing play on an unsafe ground (which is why umpires who are members of the Association of Cricket Officials have an insurance built into their membership) .  

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6. Martin,

   What is the finest resolution we can expect to find on a hospital grade scale anywhere in the world? Would it be 100 g, 10 g, or even 1 g? Does the professional boxing federation even allow measurements to be taken in kilograms? Would they insist only pounds can be the official units for measuring and recording and if a pound scale cannot be found in a metric country, one be imported for all boxing events?

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