On 2008 Mar 13 , at 10:12 AM, Tom Wade wrote:
... millimeters are particularly unsuited to measuring people's
height. They imply far too high a level of precision.
Regarding our fellow citizens who have not been trained in science or
engineering and the like, I maintain that they have no understanding
of "level of precision" at all, so it would not "imply" anything to
them.
I readily and routinely measure out 250 mL of water to heat to make a
cup of tea and am completely aware that the "250" does not mean that I
have measured to the nearest 1 mL. I do not find it necessary to
specify that the cup holds 0.25 L of boiling water in order to
indicate that the precision is at the level of +/-10 mL.
I am completely familiar with the concept of precision and significant
figures and I can (and do) use them where appropriate. But the concept
of significant figures is sometimes not significant in the
presentation of information. I think a person's height is usually one
of these cases.
If I were to want to tell you my height, including the precision with
which I measured it, I would report that I was 1.81 m tall. If someone
wants to tell how I rank in height among people in a crowd, they could
do it with my height as 1810 mm just as well*.
In addition to not knowing about precision, many people also do not
like to use decimal fractions. (I'm not one of them!) THAT is the
reason to use millimetres rather than metres.
Bill Hooper
1810 mm tall
Fernandina Beach, Florida, USA
* Or I could use 181 cm, although Pat Naughtin has persuaded me that
it is better to use millimetres than to use centimetres, for
everything. I'll refer to Pat's eloquent and well reasoned arguments,
which he has so well stated elsewhere, rather than repeat them all here.
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SImplification Begins With SI.
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