On 19/12/12 12:23, Daniel Kinzler wrote:
I don't think we can sensibly support
historical units with unknown
conversions,
because they cannot be compared directly to SI units. So, they
couldn't be used
to answer queries, can't be converted for display, etc - they arn't
units in any
sense the software can understand. This is a solvable problem, but
would add a
tremendous amount of complexity.
Ah, but they could still be meaningfully compared to each other. And if
approximate conversion is known, this could be still be used to make the
conversion so that the measure is converted and its uncertainty increased.
Just throwing more info here: there might also be cases where we could
have multiple competing conversions. Somewhat similar to units,
something that I would very much like to see is comparison of various
monetary values, adjusted for inflation or exchange rate. But then you
would have various estimates of inflation by various bodies and you
might want to compare by either of them (or a combination of them?).
Appropriate conversion might also depend on the item in question. For
example, old censuses sometimes measure population not in people but in
households. In some cases we might have the idea of how large a
household is to give estimate of the population.