Come off it, Mr Cox! (letters, 14 August) Are you really saying that "kilograms per square metre" make sense as units to express body mass index? Like pounds per square inch, kg/m2 are units of pressure? The BMI is the ratio of the number of kilograms a person weighs to the square of the number of metres he or she is in height, and as such is just a number, no units attached.
Fortunately, today's Indy contains the following...
Jonathan Phillips seems unaware of the difference between mass and force (letters, 15 August). The units of pressure are not kilograms per square metre, but newtons per square metre or pounds-force per square inch. Units are essential for BMI: a man 1.83m tall and weighing 74kg has a perfectly healthy BMI of 22kg/m2. If he expressed himself as 6ft and 11st 9lbs, his BMI would be 0.32 stones/ft2. Both are correct and the unit is everything.
But why did they publish the first letter, are we in point and laugh mode, or does yer clueless arts-grad journo not know the difference between an opinion and the statement of something mathematically incorrect?
Not that the latter letter makes a great deal of sense, although it does get to the hub of the matter, that it is not a dimensionless ratio.