On 19 December 2012 15:11, Daniel Kinzler <daniel.kinz...@wikimedia.de> wrote: > If they measure the same dimension, they should be saved using the same unit > (probably the SI base unit for that dimension). Saving values using different > units would make it impossible to run efficient queries against these values, > thereby defying one of the major reasons for Wikidata's existance. I don't > see a > way around this.
Daniel confirms (in separate mail) that Wikidata indeed intends to convert any derived SI units to a common formula of base units. Example: a quantity like "1013 hektopascal", the common unit for meterological barometric pressure (this used to be millibar), would be stored and re-displayed as 1.013 10^5 kg⋅m−1⋅s−2 I see several problems with this approach: 1. Many base units are little known. "kg⋅m2⋅s−3⋅A−2" for Ohm... It breaks communication with humans curating data on wikidata. It will make it very difficult to compare data entered into wikidata for correctness, because the data displayed after saving will have little relation with the data entered. This makes Wikidata inherently unsuitable for an effort like Wikipedia with many authors and the reliance on fact checking. 2. Even for standard base units, there is often a 1:n relation. e,g, both gray and sievert have the same base unit. The base unit for lumen is candela (because the steradians is not a unit, but part of the derived unit applicability definition) Gregor _______________________________________________ Wikidata-l mailing list Wikidata-l@lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/wikidata-l
