daniel added a subscriber: Denny. daniel added a comment. In https://phabricator.wikimedia.org/T68580#1447920, @kaldari wrote:
> @daniel: Wikipedia manages to do sensible automatic unit conversion without > specifying uncertainty (probably by looking at the number of digits), so why > can't Wikidata? No it doesn't - have a look at https://en.wikipedia.org/wiki/Template:Convert It uses a sensible default, but in many cases, you actually have to specify the precision explicitly. > I realize that setting the default uncertainty to 0 is wrong for > measurements, but couldn't null be the default, and the conversion script > switch to using number of digits in the case of null uncertainty? That's pretty much what we do: if no uncertainty is specified, we look at the number of digits to determine it. We could also do this upon conversion, but then we'd need to store an extra flag for "auto precision" - using 0 for this would make it impossible to force absolute exactness in the cases it is required (these are rare but important - one use case is the definition of units in relation to other units, see Significance_arithmetic <https://en.wikipedia.org/wiki/Significance_arithmetic>). > Also, I believe the implied uncertainty of whole number measurements is > +/-0.5, not +/-1. That was also my intuition, but @Denny convinced me that this was wrong. Reading up on this now, Accuracy_and_precision#Quantification <https://en.wikipedia.org/wiki/Accuracy_and_precision#Quantification> seems to support your (and my) intuition. The only thing I could quickly find in support of Denny's version is Significant_figures#Estimating_tenths <https://en.wikipedia.org/wiki/Significant_figures#Estimating_tenths>, but it doesn't really seem to apply. TASK DETAIL https://phabricator.wikimedia.org/T68580 EMAIL PREFERENCES https://phabricator.wikimedia.org/settings/panel/emailpreferences/ To: daniel Cc: Denny, Stryn, Mbch331, Sjoerddebruin, AmaryllisGardener, Izno, Smalyshev, kaldari, Gareth, Ayack, geraki, Bugreporter, DSGalaktos, Wikidata-bugs, SPQRobin, jayvdb, Snaterlicious, Liuxinyu970226, Lydia_Pintscher, daniel, aude, Malyacko, P.Copp _______________________________________________ Wikidata-bugs mailing list [email protected] https://lists.wikimedia.org/mailman/listinfo/wikidata-bugs
