I haven't taken a strong position on the centi- prefix, but you made one
argument earlier that
people keep making, and I want to point out that it doesn't seem a good
argument: "using
millimeters implies an inappropriate level of accuracy".
The choice of unit does not imply a particular level of accuracy. Never has.
Though people
seldom care about mass down to the gram, things like "250 grams" are quite
common. You rarely see
dekagrams, at least in the west. Centiliters exist, but are rare. So are
decimeters, despite the
fact that they are a very convenient size. Adding a zero or two isn't really a
problem.
--- Tom Wade <[EMAIL PROTECTED]> wrote:
> Now consider a garment industry using cm.
> For the purpose of clothes size, cm is about the precision you need (mm
> is far too precise). However, although you are moving to whole numbers,
> you are moving from whole number of inches (or at worst 1/2 inches) so
> the gain in ease of use is not as marked, and is therefore less likely
> to overcome the inertia of changing from something familiar. If the
> garment industry had chosen mm, you would then have units that would be
> over-precise (imagine what the clothes rail signs would look like). You
> would be moving to something *less* convenient than what you had. Just
> because mm is the more appropriate unit for most sectors doesn't mean it
> is the one for all of them. Yes, the choice of cm did affect the pace
> of metrication, not because it was the wrong choice (mm would have been
> much worse) but because it didn't provide the same large leap forward in
> convenience over what existed beforehand than was experienced going from
> fractional inches to millimeters.
I'm not sure how something can be "over-precise". The clothes rail signs would
look fine, they
would just have one more digit than you're accustomed to. I thought the
argument (and I'm still
not taking sides here -- I have no problem with centimeters) was that if you
switch to
centimeters, people use them like inches by force of habit. That is, since
they're similar in
size to inches, people use fraction expressions like "half centimeter" and have
trouble becoming
fully decimal in their habits. If you force them to use a size small enough
that fractions would
be absurd, they do things the right way and learn to think decimal.
I agree with you that the argument that millimeters make everything better is
hard to believe
without a good, systematic study on the subject. I'd very much like to see
that myself.
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