Pierre,
Please tell me where in the SI Brochure the "rule of 1000" can be found.
I don't seem to see it in my copy.
Jim
Pierre Abbat wrote:
On Friday 28 November 2008 17:15:15 Bill Hooper wrote:
This is not just a matter of deciding which unit has "advantages" over
the other; the units "mg/dL" measures something different from what is
measured in "mol/L". It's like arguing that bushels are better or
worse than pounds when buying potatoes. Bushels measures volume while
pounds measures mass. One tells you how much space the potatoes occupy
while the other tells how much mass (and indirectly, weight) they have.
Potatoes and tomatoes are better measured by mass than volume. They are large
and of various sizes. If I add 100 liters of fingerling potatoes to 100
liters of Russet potatoes. the total is less than 200 liters, because the
fingerlings fit in the interstices. The masses, though, add.
As to measuring sugar, cholesterol, and other things in blood: mg/L is
preferable to mg/dL because it follows the rule of 1000 and doesn't divide a
prefix by a prefix. In mg/L, the level is from 600 to 1050, again no decimal
points. Whether mg/L is better or worse than mol/L, I can't say. As long as
one is measuring a single substance, they can be converted, and since both mg
and mol are in use in different parts of the world, it may be useful to list
both on blood test results.
Pierre
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