(I changed subject of this thread, it was "uncertainty".) Thanks, Ed. First, we have the characters ? and ~ to mean "questionable" and "approximate". I have been using "questionable" while others are using "uncertain", and we should settle on one or the other. I have no problem switching to "uncertain" . So let's say: the characters ? and ~ mean "uncertain" and "approximate". Next .. We could immediately follow ? and ~ with a measure of uncertainly or precision respectively. Of course we need to do it in a manner that (1) doesn't introduce syntactic ambiguities, and (2) meets semantic objectives. Take "uncertainty" first. If we say that ? may be followed by a measure of uncertainty we have to be careful because ? does not always end the entire string. For example: (2004)?06-1. However if we say that uncertainty is indicated by one of the letters a, b, c, d, e, then we don't introduce ambiguity because in the current draft there isn't any case where ? would be followed by one of these letters. So the question is: Are Ed's suggested set of values acceptable to indicate uncertainty: - a) Known to be correct (observed, documented etc.) - b) Likely correct ( p> 50%) - c) Possibly correct (Might be but not likely) - d) Likely incorrect (The date is expected to be wrong p ~ 0) - e) Unknown (certainty unknown). Actually I would eliminate (e); "certainty unknown" should be the default - it should not be mandatory for the ? to be followed by an uncertainly level. Next, precision. Similarly, ~ could be followed by a level of precision. Simon, would you like to propose a scheme? --Ray From: Discussion of the Developing Date/Time Standards [mailto:[log in to unmask]] On Behalf Of Edward C. Zimmermann Sent: Tuesday, February 01, 2011 10:22 AM To: [log in to unmask] Subject: Re: [DATETIME] uncertainty On Tue, 1 Feb 2011 08:57:29 -0500, Ray Denenberg wrote > Ed - can you repost your model. (I agree, we should refer to it as "reliability".) --Ray I wrote last Nov. "We could be crazy and add grade of certainty and data-quality: - a) Known to be correct (observed, documented etc.) - b) Likely correct ( p> 50%) - c) Possibly correct (Might be but not likely) - d) Likely incorrect (The date is expected to be wrong p ~ 0) - e) Unknown (certainty unknown). (1985)? with the grade (a) is equivalent to 1985. 198u says that its known (a) that the date in the 1980s. The 'u' says we know nothing more. Going back to by example about the date of the Great Flood and the birthdate of... " There are well other nauances of data reliability but I think with the qualitative segments of observed/documented (highly certain), likely OK, possibly OK, likely wrong and who knows one probably covers the typical conversational predicates.. > > > From: Discussion of the Developing Date/Time Standards [mailto:[log in to unmask]] On Behalf Of Edward C. Zimmermann > Sent: Tuesday, February 01, 2011 7:29 AM > To: [log in to unmask] > Subject: Re: [DATETIME] uncertainty > > If uncertainty one must start off with a model of how to describe uncertainty. I provided one such model some time ago. There are others. That is the starting point. I see these as modifiers to our unknown predicate. The term really should be "reliability" rather than unknown or uncertain. A date, after all, that is unknown is unknown. Reliability and trust in the correctness of a given date, by contrast, can be qualitatively described: a continuum from probably wrong to highly certain. -- Edward C. Zimmermann, NONMONOTONIC LAB http://www.nonmonotonic.net <http://www.nonmonotonic.net/> Umsatz-St-ID: DE130492967