For those who enjoy story problems, it is most accurate for people who are 2 m tall. It irrationally predicts that people who are 1 m tall should be weightless, rather than having 1/4 the weight of a 2 m tall person. It approximates a quadratic function with a linear one, but the weightless 1 m people adequately explain why it works poorly for children, and generally underestimates for people appreciably shorter than 2 m.
________________________________ From: Pat Naughtin <[email protected]> To: U.S. Metric Association <[email protected]> Sent: Thu, January 28, 2010 9:30:49 PM Subject: [USMA:46510] For adults only On 2010/01/29, at 12:28 , Harry Wyeth wrote: Wednesday's (or maybe it was Tuesday) Wall Street Journal carried a rather long article on body fat which contained a discussion of body mass index (BMI). To my amazement, BMI was described accurately as by weight (oops...mass) in kilos divided by height in meters squared. There was no mention of the convoluted English formula. I think I will send them a congratulatory email. > >HARRY WYETH > Dear Harry, Some time ago I noticed that the Body Mass Index was a little too complex for many (perhaps most) folk to calculate. I tried this approach: 1 Enter you mass in kilograms into your calculator (say 115 kilograms). 2 Touch the divide ÷ button. 3 Enter your height in metres (say 1.85 metres). 4 Touch the divide ÷ button again. 5 Enter your height in metres (still 1.85 metres). 6 Touch the equals = button. The BMI for our example will be 33.6 kg/m^2 so we find that this person is obese after we look up a chart. Even with this step-by-step approach, I still had two problems with this: you need a calculator and you need a chart. So I invented this alternative method to use as a rule of thumb for your body mass: 1 Think of your height in metres (say) 1.85 metres. 2 Remove '1 metre' and the decimal point '.' 3 You are left with the number: '85'. You can consider this as the upper limit of your normal body mass in kilograms, that is 85 kilograms. You could think of this as your NaughtinDEX – tee hee! Any more than this and you will be classified as overweight; 10 % more than this (93.5 kg) would be classed as overweight, and 20 % more than this (102 kg) would be classed as obese. Why is this for adults only? Because this rule does not seem to work for children. Cheers, Pat Naughtin Author of the ebook, Metrication Leaders Guide, that you can obtain from http://metricationmatters.com/MetricationLeadersGuideInfo.html PO Box 305 Belmont 3216, Geelong, Australia Phone: 61 3 5241 2008 Metric system consultant, writer, and speaker, Pat Naughtin, has helped thousands of people and hundreds of companies upgrade to the modern metric system smoothly, quickly, and so economically that they now save thousands each year when buying, processing, or selling for their businesses. Pat provides services and resources for many different trades, crafts, and professions for commercial, industrial and government metrication leaders in Asia, Europe, and in the USA. Pat's clients include the Australian Government, Google, NASA, NIST, and the metric associations of Canada, the UK, and the USA. See http://www.metricationmatters.com/ to subscribe.
