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