On 19.12.2012 16:41, Marco Fleckinger wrote:
I assume there's a table for usual units for
different purposes. E.g. altitudes
are displayed in m and ft. Out of that one of those is chosen by the user's
locale setting. My locale-setting would be kind of "metric system", therefore
it
will be displayed in m on my wikidata-surface. On enwiki it will probably be
displayed in ft.
I'd have thought that we'd have one such table per dimension (such as
"length"
or "weight"). It may make sense to override that on a per-property basis, so
2300m elevation isn't shown as 2.3km. Or that can be done in the template that
renders the value.
My suggestion would be:
* Somebody types in 4.10, so 4.10 will be saved. There is no accuracy available
so n/a is been saved for the accuracy or even the javascript way could be used,
which will be undefined (because not mentioned). Retrieving this will result in
4.10 or {value:4.10}.
What is saved would depend on unit conversion, the value actually stored in the
database would be in a base unit. In addition, the input'S precision would be
usewd to derive the value'S accuracy: entering 4.10m will make the accuracy
default to 10cm (+/- 5cm).
Futhermore, a
quantity may be given as 4.10-4.20-4.35. The precision
of measurement and the the measure of variance and dispersion are
separate concepts.
Hm, somewhere in the scope of mechanical engineering there are also existing
±-values where the tolerances up and down differ from each other. E.g: it should
be 11.2, but it may be 11.1 or 11.35.
I'd suggest to store such additional information in a Qualifier instead of the
Data Value itself.
I fear that is
a view of how data in a perfect world should be known,
not a reflection of the kind of data that people need to store in
Wikidata. Very often only the precision will be known or available to
its authors, or worse, the source may not say which it is.
I think this is kind of Wikidata definitions. Since years now precision is used
for the amount of digits behind the comma. Now we need another word for
expressing how accurate a value is. Therefore: Do we have a glossary?
Indeed we do:
https://wikidata.org/wiki/Wikidata:Glossary
I use "precision" exactly like that: significant digits when rendering output
or
parsing intput. It can be used to *guess* at the values accuracy, but is not the
same.
-- daniel
--
Daniel Kinzler, Softwarearchitekt
Wikimedia Deutschland - Gesellschaft zur Förderung Freien Wissens e. V.