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.
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