XPost: sci.electronics.equipment   
   From: presence@MUNGEpanix.com   
      
   In sci.electronics.equipment Pimpom  wrote:   
   > On 6/20/2020 4:29 AM, Commander Kinsey wrote:   
   >> On Fri, 19 Jun 2020 23:55:42 +0100, Ralph Mowery  wrote:   
   >>   
   >>> In article , CFKinsey@military.org.jp says...   
   >>>>   
   >>>> But what I'm surprised at is a ?5 multimeter (not clamp) not giving a   
   digits error.  Maybe precision on a simple voltmeter is cheap as chips   
   nowadays?   
   >>>>   
   >>>>   
   >>>   
   >>> You have to be careful how you throw precision and accurecy around.   
   >>>   
   >>> A meter that shows 4 digits is more precice than one that shows only 3   
   >>> digits, however the 4 digit one may only be 1% accurate and the 3 digit   
   >>> one may be .5% accurate.   
   >>>   
   >>> It is easy to get precision, but difficule to be accurate.  Think of it   
   >>> as shooting a gun.  Precision may be how close the bullets land to each   
   >>> other where ever they land on the target, but to be accurate the bullets   
   >>> have to land on the center of the target.  Such as all the bullets could   
   >>> land very close to each other, but not even hit the target.   
   >>>   
   >>> As I mentioned, a good meter will not have a digits error outside the +-   
   >>> one digit due to rounding.   
   >>   
   >> That didn't help.  I interchange the two.  I just want to know how close to   
   the correct reading the readout is.  Adding another digit doesn't improve   
   anything if it's incorrect.  And shooting all the bullets in one place doesn't   
   help if they all miss.   
   >>   
   >   
   > Take pi as an example. It can be said that 3.14 is accurate as a   
   > three-digit value, but 3.1416 is more precise because it has a   
   > higher resolution.   
   >   
   > OTOH, deriving it from 22/7 or 3.1429 has the same 5-digit   
   > resolution and is just as precise as far as the number it   
   > represents is concerned but is less accurate.   
   >   
   > In this particular case, 3.1416 is both more precise and more   
   > accurate than 3.14 but that's not always the case with measurements.   
   >   
   > My mechanical slide caliper has a resolution of 0.001 inch. This   
   > means that it can display measurements with a precision of 1 mil,   
      
   What if your caliper had a resolution of 1 mil +/- 3 counts on the last   
   digit? That's the issue with multimeters that have completely bogus digits   
   at the end. Those number are just noise and serve no purpose at all. They   
   don't even compare to all bullets missing the target but landing in the   
   same wrong spot.   
      
   > but that doesn't guarantee that a measurement taken with it will   
   > be accurate to 1 mil. I may not always press the jaws snugly   
   > enough and the scale may not be perfectly accurate.   
      
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