calibrated – a Janus word?

Discuss word origins and meanings.

calibrated – a Janus word?

Post by dalehileman » Sat Jun 04, 2005 7:56 pm

Typically an instrument used to take a simple measurement, eg, a dc ammeter, is calibrated against a standard traceable to the National Bureau of Standards. The value may then be specified with some degree of confidence: “30 amps dc.” An ac or pulsating measurement gets to be a little trickier, as you engineering types are aware, because we then have to account for duty cycle, rms v average v effective v peak, phase angle, etc etc. Yet even in these cases we can usually declare with some assurance, “4000 Amps AC RMS effective continuous”


However, some values are not so easily specified, especially when the instrument or the standard it is calibrated against are subject to a large number of variables, when the instrument used to make the measurement has been calibrated against a standard of uncertain stability, or when the results of it use depend heavily on exactly how the calibration is performed or the measurement made


Bear with me


Back in my school days when I was keeper of a campus “wired wireless” station I was required to show that my field strength didn’t exceed certain FCC guidelines. When a Professor of Electrical Engineering volunteered to take a field-strength measurement, he asked me what that value was, assuring me that such measurements typically are so uncertain that he could get me “any result you want”


To impart a degree of confidence–without having to admit the result is only “approximately” or even worse, “roughly” accurate–the term “calibrated” is sometimes added; eg, “110 calibrated microvolts per meter.” Under these conditions, “calibrated” means uncalibrated
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Re: calibrated – a Janus word?

Post by Ken Greenwald » Sat Jun 04, 2005 11:59 pm

Dale, I don’t see CALIBRATED as a Janus word under any circumstances. The ‘calibrate’ we are talking about is defined as:
<“To determine the correct position, value, capacity, etc., of; to set an instrument so that readings taken from it are absolute rather than relative; to check, adjust, or determine by comparison with a standard (the graduations of a quantitative measuring instrument): ‘calibrate a thermometer.’”>
Now if a bad job of calibrating is done, you’ve got a poor job of calibration, but that doesn’t make ‘calibrated’ its own antonym any more than a bad ‘tune-up’ on your car would make that a Janus word – although it would make it annoying. (<)

(see Janus words (antagonyms, contronyms))
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Re: calibrated – a Janus word?

Post by dalehileman » Sun Jun 05, 2005 6:38 pm

Ken thank you. However, my point is that the word is added to a measured value--almost apologetically--when it is of questionable accuracy, lending to it a kind of contradictory aspect
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Re: calibrated – a Janus word?

Post by Ken Greenwald » Mon Jun 06, 2005 3:27 am

Dale, Are you talking about 50 years ago or are you talking about now? And, incidentally, all measurements are approximate or 'inaccurate' to some degree except perhaps if one is counting whole numbers – you’re not likely to measure 3.5 people passing through a door. But actually, when the counts are of billions of particles passing though a detector the measurement will often be approximate and when measuring just about anything else – voltage, current, electric field, magnetic field, weight, velocity, acceleration . . . the question is one of how approximate or 'inaccurate'?

I’m not familiar with the use of the word CALIBRATED being bandied about to impart a false degree of confidence and “added to a measured value--almost apologetically--when it is of questionable accuracy.” In my experience ‘calibrated’ means exactly what it says – the measurement instrument has been calibrated and the degree of accuracy (or 'inaccuracy') is provided by a +/- number or percent which can be found in the article which uses the word or in the measurement instrument specs (e.g. +/- .01 volts at a particular frequencies or in a particular frequency range). I have never heard an example of ‘calibrated microvolts/meter’ or calibrated anything being used in the way you portray, and I did a Google search and couldn’t find one either. But perhaps you have some inside information that I’m not privy to. Could you provide us with a real example (of modern vintage) of ‘calibrated microvolts/meter’ or whatever being used in the way you suggest?
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Ken – June 5, 2005
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Re: calibrated – a Janus word?

Post by dalehileman » Mon Jun 06, 2005 5:22 pm

I'll be on the lookout for one
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Re: calibrated – a Janus word?

Post by Ken Greenwald » Mon Jun 06, 2005 6:27 pm

Dale, Wasn’t there a recent example that prompted your question?

Ken – June 6, 2005
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Re: calibrated – a Janus word?

Post by dalehileman » Mon Jun 06, 2005 11:26 pm

Sure. Soon as I re-encounter it I'll let you know
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Re: calibrated – a Janus word?

Post by Erik_Kowal » Tue Jun 07, 2005 7:09 am

Dale is clearly busier in retirement than ever...
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Re: calibrated – a Janus word?

Post by dalehileman » Tue Jun 07, 2005 11:50 pm

Clearly
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Re: calibrated – a Janus word?

Post by spiritus » Wed Jun 08, 2005 5:03 am

I think it smacks of uneven-handedness when, with willy-nilly abandon, we bandy around the proper noun, GOOGLE, using it as a verb; and take issue with the idea of a bandied "almost apologetic" CALIBRATED.

Where's the justice?

Quote from a pamphlet published by Boulder, Colorado's Dept. of Tourism
...the primary atomic clocks in national metrology laboratories -- each take up as much space as a large wardrobe and keep time with an accuracy calibrated 1 part in 10^(15), or 1 second in 30 million years...
If my appointment schedule is skewed because of my reliance upon a clock that runs 1 second slower or faster in 30 million years; thirty million years from now, an apology will be nice.

Ken, If I may fawn shamelessly for a moment; your almost scary attention to details, I sincerely admire.

The information you provide to support your points is consistently (as calibrated by me) of a 99% accuracy. The other 1% is a matter of "precision".



The issue of precision is separate from accuracy. Highly precise results often depend a great deal on the high quality of instruments employed in the measurement. For example, if we measure the length of a table with a ruler that is calibrated in inches, then the precision of our measurement cannot be better than 1 inch. The same experiment performed with another ruler that is calibrated in millimeters will give a more precise result. There are times, however, that a clever procedure could produce results with high precision despite the inadequacies of the measurement tools. (An example of this is when we determine wavelength of monochromatic light using a pinhole and a common meter stick in a diffraction measurement.)
http://idol.union.edu/~malekis/QM2004/qm_stat.htm


Though CALIBRATE is not a Janus word, to my thinking, a user could choose to apply it in a context and with an implied meaning that simultaneously confirmed and contradicted its accepted meaning.
Language is a process of free creation; its laws and principles are fixed, but the manner in which the principles of generation are used is free and infinitely varied. Even the interpretation and use of words involves a process of free creation.
Author: Noam Chomsky
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Re: calibrated – a Janus word?

Post by Ken Greenwald » Thu Jun 09, 2005 5:27 pm

Spiritus, It is good to distinguish between PRECISION and ACCURACY and also CALIBRATION. But lets not ‘bandy’ these words about without understanding what they really mean.

CALIBRATION simply means that an instrument has been checked against a standard so that it agrees to that standard at a certain frequency or range of frequencies (weight or range of weights, speed or range of speeds. . . ) and within some degree of accuracy (e.g. +/- .01 kg between 0 and 10 kg). This means that the scale agrees with reality, is ACCURATE to within +/- .01 kg, in the specified range.

PRECISION, however, tells a different story. Precision is just has to do with the fineness of the markings on ones instrument. For example, the digital readout on the above lab scale may actually read to say the fourth decimal place +/- .0001 kg, but the scale has been calibrated to be accurate to only the second decimal place. This tells us that we may get an extremely precise reading that is totally inaccurate. A common example is a home bathroom digital scale that reads to a precision of tenths of a pound, but is off by 2 pounds – high precision but low accuracy.

What CALIBRATION would do for the above bathroom scale is to certify that the scale was accurate or agreed with reality at a certain weight or in a certain weight range (at least at the time of calibration). For example. If a standard 100 pound weight (certified to be 100 pounds within +/- 0.001 pounds) were to be put on your digital scale and the knob on the digital readout turned until the scale read 100.0 pounds (remember that your scale only reads to, has a precision of, +/- 0.1 pounds at most). Now scales (and many other instruments) are notoriously nonlinear so that just because your scale had been calibrated to be accurate to +/- 0.1 pounds at 100 pounds doesn’t tell us what its accuracy at 200 pounds is. If you wanted to calibrate it between 100 and 200 pounds a second standard weight of 200 pound would have to be used to see how closely the scale agreed with it, and if it were off by say 0.3 pounds at 200 pounds, then one might say that this scale was calibrated to be accurate to +/- 0.3 pounds when weighing objects that are in the range of 100 to 200 pounds or, as they do on some instruments, specify the calibrated accuracy at both 100 and 200 pounds separately.

So PRECISION does not imply ACCURACY although ‘accuracy’ does imply a certain degree of ‘precision’ – and an instrument can be calibrated to an accuracy that is no greater than its precision. For example the above bathroom scale could not be calibrated to have an accuracy of +/- .001 pounds if the digital readout is only capable of reading to 0.1 pounds. And the process of CALIBRATION involves dealing with both of these concepts.
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Ken G – June 9, 2005
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Re: calibrated – a Janus word?

Post by spiritus » Thu Jun 09, 2005 10:17 pm

Precisely!
Drawing on my fine command of the English language, I said nothing.
---- Robert Benchley
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Re: calibrated – a Janus word?

Post by verbose » Fri Jun 10, 2005 5:52 pm

Once an instrument is calibrated, proper scientific technique requires that control runs be performed. Controls have a known value and testing should yield that value, within a specific allowed variance known as a standard deviation. Test results should only be considered valid after controls indicate that the instrument is functioning properly. From an old medical laboratory tech...
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Re: calibrated – a Janus word?

Post by Edwin Ashworth » Fri Jun 10, 2005 9:07 pm

...which Groucho apparently hadn't read: "Either this guy's dead or my watch has stopped."
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Re: calibrated – a Janus word?

Post by spiritus » Sat Jun 11, 2005 1:00 am

In quantum (a Janus word physics, the instrucment used for observation may be altered by that which is observed. Obviously Groucho intuitively understood this to be a possibility.
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