I replied at https://phabricator.wikimedia.org/T105623. Lets keep the discussion there.
Am 19.09.2015 um 21:14 schrieb Michael Peel: > >> On 19 Sep 2015, at 19:16, Daniel Kinzler <[email protected]> wrote: >> >> Am 19.09.2015 um 10:27 schrieb Egon Willighagen: >>> >>> >>> On Tue, Sep 15, 2015 at 10:12 PM, Michael Peel <[email protected] >>> <mailto:[email protected]>> wrote: >>> >>> It seems to assume a default uncertainty on values, though: I just added >>> the >>> elevation above sea level to: >>> https://www.wikidata.org/wiki/Q1513315 >>> just specifying the central value, and it assumes that this value is +- >>> 0.1 >>> km - which isn't a good assumption to make... >>> >>> >>> Did you mean to write 2.80 km about sea level? Then the error would be 0.01 >>> km >>> .... I am guessing the uncertainty follows the scientific notation of the >>> number... 2.8 has the numeric uncertainty of (about) +/- 0.1... >>> >>> That sounds like a reasonable approach to me... >> >> Yes, the uncertainty follows the scientific convention about significant >> digits. > > Taking that approach is a *really* bad idea. You can't just assume/make up > uncertainties! > > As an example, say you have a length of 100m. Which significant digit do you > assume is correct? Is this +- 100m, 10m or 1m? What if it's referring to the > length of a 100m run, where the accuracy could be much higher than the > significant digit given, e.g. 100m +- 1cm? Or what if it's the size of a > crater on a distant planet, where it might be 100m+-50m? Or if the actual > value is 100m +- 3m, but we say that it's +- 1m (which I see is the default > in this case), which might be believable to readers but very misleading in > reality? > >> We are currently thinking about adjusting this a bit, see >> https://phabricator.wikimedia.org/T105623 > > As thiemowmde says there: > "The fact that the parser "guesses" a precision based on basically zero > information always was and still is wrong. It must default to ±0. Everything > else is misleading and a source of significant confusion and actual errors." > ... although perhaps a better approach if possible might be to default to -1, > or something else indicating the absence of data. > > Thanks, > Mike > > > _______________________________________________ > Wikidata mailing list > [email protected] > https://lists.wikimedia.org/mailman/listinfo/wikidata > -- Daniel Kinzler Senior Software Developer Wikimedia Deutschland Gesellschaft zur Förderung Freien Wissens e.V. _______________________________________________ Wikidata mailing list [email protected] https://lists.wikimedia.org/mailman/listinfo/wikidata
