I recall in physics class our professor making it quite clear that 'precision' and 'accuracy' are 2 different things! However, all I recall now is that they were SUPPOSED to be different but not what that difference was. I did remember where to look for the reference, tho. Here it is:
From Statistical Treatment of Experimental Data by Hugh Young: "If a measurement has small _systematic_ errors, we say that it has high accuracy; if small _random_ erors, we say it has high precision." Clem ps, I see you're from Tucson. I took physics at the UofA. :-) At 08:35 AM 04/29/1999 -0700, you wrote: >Hello Old Timers: > >I've got another knit-picky question for you all to ponder. But you're a >rather knit-picky group, so I don't think you'll mind. > >In proofreading the new fifth edition of my "Sundial Owner's Manual", when >discussing sundials, I think that I mistakenly used the words, "precise" and >"accurate", interchangeably, as if they meant the same thing. > >Is it possible to have an accurate sundial that is not precise? (I think so) > >Is it possible to have a precise sundial that is not accurate? (I think not) > >Should the word "precise' refer to sundials that have small time divisions; >ie. large sundials? (One definition of "precise" in my dictionary says >"minutely exact"). Using this definition, only large sundials with small >time divisions can be precise. A ring sundial can never be precise. Size >is everything! > >The word "accurate" is defined by my dictionary as "free from error". This >suggests that an accurate sundial is properly designed and constructed. >Does'nt it? > >There is a very large public vertical wall dial here in Tucson that appears >to have been correctly designed and constructed but it has no hour lines at >all, only numerals. It's anyone's guess what the precise time is. This >would be an example of an accurate sundial that is not precise. On the >other hand, a heliochronometer would HAVE to be precise and accurate because >it is well-made and has small (1 min?) time divisions. Right? > >Do you think my train of thought is correct? > >John Carmichael >Tucson >tel: 520-696-1709 >website: http://www.azstarnet.com/~pappas > >
